refactor(cli)!: split the contributor tool out of the ludic CLI

`ludic help` ended with a section titled "contributing to the toolchain itself",
listing bootstrap, reseed, docs-gen and release tasks. None of that is available
to someone who installed the language — those tasks need the repository — so the
shipped tool was advertising work its user cannot do, in a namespace they have to
read past to find `new` and `run`.

The tasks move to a second program, dev.ludic -> bin/ludic-dev, built from a
checkout and excluded from every release artifact. `ludic` keeps the project and
package commands and nothing else; `ludic dev …` now explains where the tasks
went instead of failing as an unknown command.

What this shook out: the two programs share prelude/build/project/pkg, so the
helpers each had accreted in whichever file first needed them — cc(),
ensure_ludicc, the string functions, title_case, cmd_version — moved to where
both can see them. The argument-shift indirection added for the `dev` namespace
is gone with the namespace, so commands read argv directly again.

`ludic-dev test` asserts the split rather than trusting it: the staged install
must build a project, and `ludic dev build` there must fail while naming
ludic-dev. install.sh keeps building older tags, whose bootstrap goes through
main.ludic.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.forgejo/pull_request_template.md

@@ -8,13 +8,13 @@ Closes #
 
 ## Checklist
 
-- [ ] `bin/ludic dev test` passes.
-- [ ] For compiler/runtime changes: `bin/ludic dev reseed && bin/ludic dev bootstrap-cfree`
+- [ ] `bin/ludic-dev test` passes.
+- [ ] For compiler/runtime changes: `bin/ludic-dev reseed && bin/ludic-dev 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`
-      (`bin/ludic dev docs-gen && bin/ludic dev docs-check build/pages` passes).
+      (`bin/ludic-dev docs-gen && bin/ludic-dev docs-check build/pages` 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/`.