fix(scripts): disclose browser-bundled packages as shipped

Moving react, shiki, katex and the markdown pipeline to devDependencies took
them out of the notices runtime tier, which tiers by declaring section — yet
their code is inside lib/client.js and the shell dist. The generator now learns
what the browser artifacts carry from the real build configs: each client bundle
through its own tsdown config, the shell through apps/web's Vite config, with a
recorder that resolves each bare specifier, notes the package behind it, and
stops there. About three seconds, and only packages a resolved file backs, so a
bundler's virtual module is not mistaken for a shipped one.

Net effect on the file: the type-only packages @types/mdast and
micromark-util-types move to the development tier, because neither ships code.

lefthook.yml

@@ -28,7 +28,7 @@ pre-commit:
     # lefthook only inspects files present on disk — so that one case still
     # falls through to the freshness assertion in the test lane.
     - name: third-party notices (staged)
-      glob: '{package.json,*/package.json,*/*/package.json,*/*/*/package.json,*/*/*/*/package.json,pnpm-workspace.yaml,*/*/pnpm-workspace.yaml,pnpm-lock.yaml,vendor/README.md,python/*/pyproject.toml,scripts/gen-third-party-notices.ts,scripts/build-exe-for-python-sdk.ts}'
+      glob: '{package.json,*/package.json,*/*/package.json,*/*/*/package.json,*/*/*/*/package.json,pnpm-workspace.yaml,*/*/pnpm-workspace.yaml,pnpm-lock.yaml,vendor/README.md,python/*/pyproject.toml,scripts/gen-third-party-notices.ts,scripts/browser-bundled-externals.ts,packages/client/tsdown.client.ts,scripts/build-exe-for-python-sdk.ts}'
       run: node_modules/.bin/tsx scripts/gen-third-party-notices.ts && git add THIRD_PARTY_NOTICES.md
 
     - name: whitespace (staged)