fix(packaging): make npm package publishable

[gmenher]

Ref: #30

Summary

Fixes the packaging issues that block the automated publish pipeline (#11).

Changes

1. Root . export — Add entry so bare import from 'openshell-dashboard' resolves correctly under modern bundlers.
2. Fix types field — Point at dist/pages/index.d.ts to match main/module (was dist/types/index.d.ts, causing type/runtime mismatch for consumers).
3. Remove duplicate peerDeps from dependencies — 9 packages (react, react-dom, react-router-dom, @patternfly/*, @tanstack/react-query) were in both peerDependencies and dependencies. Consumers got a second copy of React in their tree, breaking context hooks.
4. Add build:lib to CI — Catches packaging breakage before merge.
5. Add exports resolution verification — After build:lib, CI does npm pack + installs in a temp dir + require.resolve on all export entries. Catches broken exports maps.

NOT included (deliberate)

"type": "module" is not added. The tsconfig emits extensionless relative imports (ESNext with moduleResolution: node). Node ESM requires explicit .js extensions, so type: module would break Node-direct usage. Since the sole consumer is a bundler (webpack/rspack in odh-dashboard), this is unnecessary and would be harmful.

Testing

Verified locally:

cd frontend && npm run build:lib   # ✅ compiles clean
npm pack --pack-destination /tmp
mkdir /tmp/verify-pkg && cd /tmp/verify-pkg
npm init -y
npm install --legacy-peer-deps /tmp/openshell-dashboard-0.1.0.tgz
node -e "
  require.resolve('openshell-dashboard');
  require.resolve('openshell-dashboard/pages');
  require.resolve('openshell-dashboard/components');
  require.resolve('openshell-dashboard/api');
  require.resolve('openshell-dashboard/types');
  require.resolve('openshell-dashboard/slots');
  console.log('All exports resolve correctly');
"
# Output: All exports resolve correctly

Also verified go build ./... and go test ./... pass (backend unchanged).