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/release.yml

@@ -1,6 +1,6 @@
 name: release
 
-# Cutting a release is `ludic dev release` + `git push --tags`; everything after that
+# Cutting a release is `ludic-dev release` + `git push --tags`; everything after that
 # happens here. Before this workflow existed the artifacts were built on whatever
 # machine the maintainer happened to be sitting at, from whatever was in bin/ at
 # the time, with no checksums and nothing proving the tagged tree even passed its
@@ -71,15 +71,15 @@ 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/ludic dev build
+          bin/ludicc tools/ludic-cli/dev.ludic -o bin/ludic-dev
+          bin/ludic-dev build
 
       - name: The tagged tree must pass its own suites
         run: |
           set -eu
-          bin/ludic dev test
-          bin/ludic dev test-tools
-          bin/ludic dev bootstrap-cfree
+          bin/ludic-dev test
+          bin/ludic-dev test-tools
+          bin/ludic-dev bootstrap-cfree
 
       - name: Publish the release
         env:
@@ -91,9 +91,9 @@ jobs:
             echo "::error::No FORGEJO_TOKEN secret; cannot create the release."
             exit 1
           fi
-          # ludic dev publish builds dist/ (source tarball from the tag, this host's
+          # ludic-dev publish builds dist/ (source tarball from the tag, this host's
           # toolchain, SHA256SUMS), takes the notes from the CHANGELOG section,
           # and creates the release. Re-running it only adds missing assets, so
           # a maintainer can afterwards attach the macOS toolchain from a Mac
           # with the same command.
-          bin/ludic dev publish "$TAG"
+          bin/ludic-dev publish "$TAG"