docs: add CONTRIBUTING, code of conduct, and Forgejo templates

Contributor onboarding for the self-hosted toolchain (issue #37):

- `CONTRIBUTING.md`: prerequisites, the bootstrap one-liner, the dev loop
  (`bin/x reseed` -> `bin/x bootstrap-cfree` -> `bin/x test`), stdlib-addition
  guidance, and the code/commit conventions (Conventional Commits, ludic-fmt,
  one-job-per-file, Ludic-not-C/Python/JS for new tooling).
- `.forgejo/issue_template/`: bug, proposal, and cleanup/DX templates.
- `.forgejo/pull_request_template.md`: a checklist covering tests, the
  bootstrap fixpoint, formatting, docs/inventory, and commit style.
- `.forgejo/CODEOWNERS` and a short `CODE_OF_CONDUCT.md`.

Closes #37

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.forgejo/CODEOWNERS

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+# Default owner for everything in the repo. Forgejo requests review from these
+# owners on matching pull requests. See:
+# https://forgejo.org/docs/latest/user/code-owners/
+*       @orkun

.forgejo/issue_template/bug.md

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+---
+name: "Bug report"
+about: "Something in the compiler, runtime, or tooling behaves incorrectly"
+title: "bug: "
+labels:
+  - bug
+---
+
+## What happened
+
+<!-- A clear description of the incorrect behaviour. -->
+
+## Minimal reproduction
+
+<!-- The smallest .ludic program (or command) that triggers it. -->
+
+```ludic
+```
+
+## Expected vs actual
+
+- **Expected:**
+- **Actual:**
+
+## Environment
+
+- Command used (e.g. `bin/x app foo.ludic --headless`):
+- Target (native macOS / headless / web-wasm):
+- Commit (`git rev-parse --short HEAD`):
+- OS / arch:
+
+## Notes
+
+<!-- Stack traces, generated IR, or anything else that helps. -->

.forgejo/issue_template/cleanup.md

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+---
+name: "Cleanup / DX"
+about: "Repo hygiene, tooling, docs, or developer-experience improvements"
+title: ""
+labels:
+  - cleanup
+  - dx
+---
+
+## Problem
+
+<!-- What friction or inconsistency exists today? -->
+
+## Proposal
+
+<!-- What to change. Keep it scoped and low-risk. -->
+
+## Acceptance criteria
+
+- [ ]
+- [ ]

.forgejo/issue_template/proposal.md

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+---
+name: "Proposal"
+about: "Propose new language, stdlib, or runtime surface"
+title: "Proposal: "
+labels:
+  - proposal
+---
+
+## Summary
+
+<!-- One or two sentences: what should exist that doesn't today. -->
+
+## Motivation
+
+<!-- What can't be done cleanly now? Who needs this and why? -->
+
+## Proposed surface
+
+<!-- The namespace/API or syntax you propose. Show it in use. -->
+
+```ludic
+```
+
+## Determinism & backends
+
+<!-- Ludic's runtime is deterministic fixed-point. Does this proposal stay
+     replay-safe? Does it work on native AND web-wasm, or is it host-gated? -->
+
+## Alternatives considered
+
+## Open questions

.forgejo/pull_request_template.md

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+<!-- Thanks for contributing to Ludic! Please fill in the checklist below. -->
+
+## What & why
+
+<!-- What does this change and why? Link the issue: Closes #NN -->
+
+Closes #
+
+## Checklist
+
+- [ ] `bin/x test` passes.
+- [ ] For compiler/runtime changes: `bin/x reseed && bin/x bootstrap-cfree`
+      still reaches the self-hosting fixpoint with no C compiler in the loop.
+- [ ] `ludic-fmt` leaves the touched files unchanged (2-space, LF, UTF-8).
+- [ ] New/changed stdlib symbols are documented under `docs/language/**` and
+      registered in `tools/docgen/inventory.json`
+      (`python3 tools/docgen/check.py` passes).
+- [ ] Commits follow [Conventional Commits](https://www.conventionalcommits.org).
+- [ ] No new C / Python / JS in tooling (Ludic only), and no generated
+      artifacts committed outside `build/` / `bin/`.
+
+## Notes for reviewers
+
+<!-- Anything reviewers should look at closely, or follow-ups deferred. -->

CODE_OF_CONDUCT.md

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+# Code of Conduct
+
+## Our standard
+
+Ludic is a small, focused project. Everyone taking part — filing issues,
+proposing changes, reviewing, or discussing — is expected to keep it a
+respectful, harassment-free place to collaborate, regardless of background or
+experience level.
+
+**Do:** be direct and kind, critique code rather than people, assume good
+faith, and keep discussion technical and on-topic.
+
+**Don't:** harass, insult, demean, or discriminate; post others' private
+information; or derail threads with personal attacks.
+
+## Scope
+
+This applies to all project spaces — the issue tracker, pull requests, and any
+official channels — and to public spaces when someone is representing the
+project.
+
+## Enforcement
+
+Report unacceptable behaviour to the maintainer at **orkun@workshopsoft.io**.
+Reports are handled confidentially. Maintainers may edit or remove contributions
+that violate this code, and may temporarily or permanently bar anyone whose
+behaviour is judged harmful.

CONTRIBUTING.md

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+# Contributing to Ludic
+
+Thanks for your interest in Ludic — an AoT-**compiled** game language with an
+ECS core, a deterministic fixed-point runtime, and a native 2D backend. This
+guide covers the unusual bit: Ludic is **self-hosted**, so the compiler, the
+runtime, and the tooling are all written in Ludic and built by Ludic.
+
+## Prerequisites
+
+- `clang` (or another C compiler) — used **once** to assemble the checked-in
+  LLVM-IR seed into the first `ludicc`, and thereafter only to assemble IR and
+  link. No C is generated in a build.
+- LLVM (for the web/wasm target: `brew install llvm lld`).
+- macOS for the windowed Cocoa backend; headless PPM rendering works anywhere.
+
+## First build (bootstrap)
+
+From a clean checkout, one line lifts the toolchain off the seed:
+
+```bash
+clang selfhost/ludicc.seed.ll -o bin/ludicc && bin/ludicc tools/x/main.ludic -o bin/x
+```
+
+That gives you `bin/x`, the Ludic task runner that replaces every build/test
+shell script in the repo. From then on it builds everything — including itself:
+
+```bash
+bin/x build          # rebuild the whole toolchain into bin/ (ludicc, ludic, x, ludic-fmt, ludic-lsp)
+bin/x help           # list every command
+```
+
+Always run `x` from the repository root, so `assets/` and `selfhost/` resolve.
+
+## The development loop
+
+When you change the compiler or runtime, prove the self-hosting fixpoint still
+holds before you push:
+
+```bash
+bin/x reseed          # regenerate selfhost/ludicc.seed.ll after a compiler change
+bin/x bootstrap-cfree # rebuild the compiler from the seed with NO C compiler in the loop
+bin/x test            # the full regression suite
+```
+
+Other useful targets:
+
+```bash
+bin/x app <file.ludic> [--headless]   # compile a program to a native app in build/
+bin/x selfhost-test                   # correctness + bootstrap fixpoints
+bin/x test-tools                      # the editor-toolchain suite (ludic-fmt, ludic-lsp)
+bin/x clean                           # remove build/, out.ppm and stray artifacts
+```
+
+## Adding to the standard library
+
+The stdlib lives in the runtime (`runtime/`) and is surfaced as namespaces
+(`Math.*`, `Crypto.*`, `DateTime.*`, `Screen.*`, …). When you add a symbol:
+
+1. Implement it in the runtime / emitter as appropriate.
+2. Document it: add one Markdown file per symbol under `docs/language/<namespace>/`
+   and register its id in `tools/docgen/inventory.json`. Each documented
+   namespace gets exactly **one** directory (the docs check enforces this).
+3. Add or extend an example under `examples/` and a case in the test suite.
+4. Run `python3 tools/docgen/gen.py && python3 tools/docgen/check.py` — the
+   check fails if any inventory symbol lacks a page or is still seed text.
+
+## Conventions
+
+- **Commits:** [Conventional Commits](https://www.conventionalcommits.org) —
+  `type(scope): summary`, e.g. `feat(stdlib): …`, `fix(emit): …`,
+  `ci(docs): …`, `docs(readme): …`. Keep the summary imperative and under ~72
+  chars.
+- **Formatting:** `ludic-fmt` is the source of truth (2-space indent, LF, UTF-8);
+  the repo `.editorconfig` mirrors it. Run `bin/ludic-fmt` on files you touch.
+- **Code structure:** one job per file. Split large files by concern into
+  subfolders rather than growing a single 500+-line module (see how `selfhost/`
+  and `runtime/` are organised).
+- **Language of the toolchain:** new runtime and tooling are written in **Ludic**,
+  not C, Python, or JS. The only non-Ludic pieces are the LLVM-IR seed
+  (`selfhost/ludicc.seed.ll`), the hand-written `runtime/native/cocoa.ll` /
+  `runtime/web/wasm.ll` shims, and the legacy Python docgen (being ported).
+
+## Pull requests
+
+- Base your branch on `main`.
+- Ensure `bin/x test` (and `bin/x bootstrap-cfree` for compiler/runtime changes)
+  pass, and that `ludic-fmt` leaves your files unchanged.
+- Fill in the PR template checklist. Reference the issue you close with
+  `Closes #NN` in the description or a commit message.
+
+## Reporting issues
+
+Use the templates under [`.forgejo/issue_template/`](.forgejo/issue_template):
+a **bug report**, a **proposal** (new stdlib/language surface), or a
+**cleanup/DX** task. Choose the one that fits and fill in the sections.
+
+By participating you agree to the [Code of Conduct](CODE_OF_CONDUCT.md).