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>

CODE_OF_CONDUCT.md

@@ -0,0 +1,27 @@
+# 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.