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/workflows/bootstrap.yml

@@ -43,11 +43,11 @@ jobs:
           set -eu
           mkdir -p bin
           clang-16 tools/ci/linux_stdio_shim.ll selfhost/ludicc.seed.ll -o bin/ludicc
-          bin/ludicc tools/ludic-cli/main.ludic -o bin/ludic
+          bin/ludicc tools/ludic-cli/dev.ludic -o bin/ludic-dev
 
       - name: Rebuild the compiler from the seed and assert byte-identity
-        # `ludic dev bootstrap-cfree` assembles the seed with clang, has that seed
+        # `ludic-dev bootstrap-cfree` assembles the seed with clang, has that seed
         # compiler recompile selfhost.ludic to out.ll, and `cmp`s out.ll against
         # the checked-in seed. It returns non-zero if they differ — i.e. if the
         # seed is stale relative to the compiler source.
-        run: bin/ludic dev bootstrap-cfree
+        run: bin/ludic-dev bootstrap-cfree