feat: add README rendering and enhanced package metadata display

**Database Schema:**
- Add npmReadme, npmKeywords, npmAuthor, npmMaintainers fields to Tool model

**NPM Client:**
- Add fetchLatestPackageWithMetadata() function to fetch README and top-level metadata
- Export new PackageVersionWithReadme type

**Sync Workers:**
- Update keyword and changes sync to fetch and store README content
- Store author, maintainers, and keywords from package.json

**UI Components:**
- Create Markdown component using react-markdown with GitHub Flavored Markdown
- Add rehype-sanitize for security and remark-gfm for tables/strikethrough support

**Tool Detail Page:**
- Convert from createElement to JSX for better maintainability
- Display README in a dedicated card with proper markdown rendering
- Show NPM keywords, author, and maintainers in sidebar
- Add ThemeToggle to header
- Improve layout with better spacing and organization

This brings the tool detail pages much closer to NPM's package pages,
providing users with comprehensive information about each tool including
the full README documentation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/package.json

@@ -21,6 +21,10 @@
     "next-themes": "^0.4.6",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
+    "react-markdown": "^10.1.0",
+    "rehype-raw": "^7.0.0",
+    "rehype-sanitize": "^6.0.0",
+    "remark-gfm": "^4.0.1",
     "zod": "^3.24.1"
   },
   "devDependencies": {