chore: migrate from npm workspaces to pnpm

[kraenhansen]

Motivation: pnpm's recursive runner (pnpm -r run) is fail-fast by default
and runs in topological (dependency-graph) order, so the root bootstrap
and prerelease no longer need the non-fail-fast npm run <s> --workspaces
pattern that buried the real root cause under cascading failures.

Workspace + package manager:

• Replace the root workspaces array with pnpm-workspace.yaml
• Add packageManager: pnpm@10.33.0 and switch devEngines to pnpm ^10
• Allow only esbuild's build script via onlyBuiltDependencies (pnpm 10 blocks
  dependency lifecycle scripts by default); no shamefully-hoist needed
• Replace package-lock.json with pnpm-lock.yaml; keep node_modules isolated

Internal deps -> workspace:* protocol (cmake-rn, ferric, gyp-to-cmake, host,
node-addon-examples, node-tests, ferric-example, test-app). Add explicit
weak-node-api edges to node-addon-examples and node-tests so the topological
bootstrap sequences weak-node-api (which builds the xcframework/.so they link)
before its consumers.

Phantom dependencies surfaced by pnpm's isolated node_modules (npm hoisting
had masked these):

• host: add @types/babel__core (used by src/node/babel-plugin/plugin.ts)
• host: add weak-node-api as a devDependency (used by
  scripts/generate-injector.mts; previously only a peerDependency)

Scripts:

• bootstrap: tsc --build && pnpm -r run bootstrap (fail-fast, topological)
• prerelease/release: make the build explicit instead of relying on npm's
  implicit prerelease hook (pnpm disables pre/post scripts by default)
• test: pnpm --filter ... run test
• depcheck/run-in-published: replace npm query .workspace with pnpm ls -r
• Pin prettier to 3.6.2: 3.7+ is incompatible with @prettier/plugin-oxc@0.0.4
  (regenerating any lockfile floated it to 3.9.5 and crashed the plugin)

CI: port check.yml and release.yml to pnpm (pnpm/action-setup, cache: pnpm,
pnpm install --frozen-lockfile, --filter, pnpm exec). The ephemeral,
non-workspace macOS test app keeps its own npm install in
scripts/init-macos-test-app.ts.

Co-Authored-By: Claude Opus 4.8 noreply@anthropic.com
Claude-Session: https://claude.ai/code/session_01DnwodAoNbqPec77191HVXn