migrate from yarn 1 to pnpm

- switch root package manager to pnpm 10.33.4 via packageManager field
- add .npmrc with node-linker=hoisted for RN/Expo compatibility
- convert yarn resolutions to pnpm.overrides; pin psl@1.9.0 and @types/psl@1.1.1
  to keep types resolving under exports-aware resolution
- pin react-compiler-runtime and babel-plugin-react-compiler to real rc.3 (the
  deprecated "Wrong version name was published" tag would otherwise resolve)
- add pnpm.onlyBuiltDependencies allowlist for @sentry/cli, core-js-pure,
  esbuild, unrs-resolver
- regenerate pnpm-lock.yaml; delete yarn.lock; drop postinstall-postinstall
- update all workflows, Dockerfile, Dockerfile.embedr (root-level), Makefile,
  conductor.json; bskyembed/bskylink/bskyogcard/dev-env stay on yarn
- update docs (CLAUDE.md, docs/build.md, docs/testing.md, docs/localization.md,
  bskyweb/README.md, scripts/push-notification/README.md, BlueskyClip/README.md)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -65,11 +65,11 @@ RUN \. "$NVM_DIR/nvm.sh" && \
   echo "EXPO_PUBLIC_BUNDLE_IDENTIFIER=$EXPO_PUBLIC_BUNDLE_IDENTIFIER" >> .env && \
   echo "EXPO_PUBLIC_BUNDLE_DATE=$(date -u +"%y%m%d%H")" >> .env && \
   echo "EXPO_PUBLIC_SENTRY_DSN=$EXPO_PUBLIC_SENTRY_DSN" >> .env && \
-  npm install --global yarn && \
-  yarn && \
-  yarn intl:build 2>&1 | tee i18n.log && \
+  npm install --global pnpm@10.33.4 && \
+  pnpm install --frozen-lockfile && \
+  pnpm intl:build 2>&1 | tee i18n.log && \
   if grep -q "invalid syntax" "i18n.log"; then echo "\n\nFound compilation errors!\n\n" && exit 1; else echo "\n\nNo compile errors!\n\n"; fi && \
-  SENTRY_AUTH_TOKEN=$SENTRY_AUTH_TOKEN SENTRY_RELEASE=$EXPO_PUBLIC_RELEASE_VERSION SENTRY_DIST=$EXPO_PUBLIC_BUNDLE_IDENTIFIER yarn build-web
+  SENTRY_AUTH_TOKEN=$SENTRY_AUTH_TOKEN SENTRY_RELEASE=$EXPO_PUBLIC_RELEASE_VERSION SENTRY_DIST=$EXPO_PUBLIC_BUNDLE_IDENTIFIER pnpm build-web
 
 # DEBUG
 RUN find ./bskyweb/static && find ./web-build/static