chore: standardize config, MCP, agents, and docs

- Add .headlamp-plugin/, .env, .env.local, .eslintcache to .gitignore
- Create .prettierrc.js (standard Headlamp prettier config)
- Fix .mcp.json typo (http:/ → http://), add github server, use localhost:8086 for playwright
- Add "github" to .claude/settings.local.json enabled servers
- Create .claude/agents/ with 3 meta-orchestration agents
- Add FilesystemsPage.tsx and ObjectStoresPage.tsx to CLAUDE.md architecture tree
- Add ArtifactHub badge, Plugin Manager install method, and Troubleshooting section to README.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -1,4 +1,8 @@
 node_modules/
 dist/
+.headlamp-plugin/
 *.tar.gz
-.playwright-mcp/
+.env
+.env.local
+.eslintcache
+.playwright-mcp/