feat: Initial tenant Control Panel

Privacy-first settings dashboard for LetsBe Cloud tenants.
- Next.js 15 (App Router) with Keycloak SSO via NextAuth.js v5
- Tool status grid with health indicators
- Settings pages (email, domain, server info)
- Post-provisioning setup checklist
- Orchestrator API proxy for server management
- Docker deployment ready

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

.gitignore

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+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env*.local
+.env
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts