feat(compiler): add @videojs/compiler package

Introduce the build-time compiler for constrained-JSX skins, rebased onto
current main as a clean, additive package. Provides:

- core pipeline: parse, compile, generate, JSX runtime, define-component
- transforms: import rewriting, replace/wrap, drop-unused locals/imports
- matchers + react lowering (add-prop, child-as-prop)
- styles className analyzer
- tailwind subsystem: design-system loader, decompose, evaluator,
  deriveClassName, emitCss, tailwindPlugin (three targets)

Self-contained: the integration smoke test now reads a vendored skin
fixture instead of the skins package, so the compiler builds and tests
green independently. 158 tests pass.

Wiring: register the project reference (tsconfig), commitlint scope,
CI test-matrix entry, and lockfile entries (lightningcss, tailwindcss).

The skin migration that consumes this compiler is parked separately —
its token refactor conflicts with skin work that landed on main; see the
follow-up commit and .claude/plans/compiler-rebase-audit.md.

.github/workflows/ci.yml

@@ -86,6 +86,7 @@ jobs:
       matrix:
         package:
           - '@videojs/cli'
+          - '@videojs/compiler'
           - '@videojs/core'
           - '@videojs/store'
           - '@videojs/utils'