chore: improve SEO and discoverability

[vish288]

Summary

• Update GitHub description to include tool count (76) and target keywords (Claude, Cursor, VS Code)
• Set GitHub homepage to PyPI page
• Optimize GitHub topics: remove low-value (gemini-cli-extension, api-integration, mcp-tools, automation, llm), add cursor, vscode, self-hosted-gitlab, fastmcp, windsurf
• Add self-hosted GitLab messaging to README (captures "self-hosted gitlab mcp" long-tail)
• Add text links (PyPI, MCP Registry, Changelog) after badges for better crawler indexing
• Add Related MCP Servers cross-linking section
• Expand PyPI keywords with cursor, vscode, windsurf, self-hosted, fastmcp, gitlab-integration
• Add Framework :: Pydantic :: 2 classifier and Documentation project URL
• Sync server.json version to 0.6.8 and update description

Test plan

• Verify GitHub repo page shows updated description and homepage link
• Verify GitHub topics are correct (20 total)
• Verify PyPI metadata renders correctly after next release
• Verify MCP Registry listing picks up server.json changes
• Check README renders correctly on GitHub (self-hosted line, text links, related servers section)