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>

examples/lang/scenes.ludic

@@ -12,7 +12,7 @@
 #     201 900  frame 3: Play.World.Step, then Hud.Draw
 #     202 900  frame 4: Step reaches 2 -> quit(); Hud.Draw paints the last frame
 #
-#   bin/ludic dev game-build bin/ludicc examples/lang/scenes.ludic /tmp/scenes
+#   bin/ludic-dev game-build bin/ludicc examples/lang/scenes.ludic /tmp/scenes
 #   printf 'aaaa' | /tmp/scenes
 program SceneDemo {
   var counter: int = 0