feat: implement frontend video platform configuration and abstraction

- Add NEXT_PUBLIC_VIDEO_PLATFORM environment variable support
- Create video platform abstraction layer with factory pattern
- Implement Whereby and Jitsi platform providers
- Update room meeting page to use platform-agnostic component
- Add platform display in room management (cards and table views)
- Support single platform per deployment configuration
- Maintain backward compatibility with existing Whereby integration

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

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

www/.env.template

@@ -0,0 +1,46 @@
+# NextAuth configuration
+NEXTAUTH_SECRET="your-secret-key"
+NEXTAUTH_URL="http://localhost:3000/"
+
+# API configuration
+NEXT_PUBLIC_API_URL="http://127.0.0.1:1250"
+NEXT_PUBLIC_WEBSOCKET_URL="ws://127.0.0.1:1250"
+NEXT_PUBLIC_AUTH_CALLBACK_URL="http://localhost:3000/auth-callback"
+NEXT_PUBLIC_SITE_URL="http://localhost:3000/"
+
+# Environment
+NEXT_PUBLIC_ENV="development"
+ENVIRONMENT="development"
+
+# Video Platform Configuration
+# Options: "whereby" | "jitsi" (default: whereby)
+NEXT_PUBLIC_VIDEO_PLATFORM="whereby"
+
+# Features
+NEXT_PUBLIC_PROJECTOR_MODE="false"
+
+# Authentication providers (optional)
+# Authentik
+AUTHENTIK_CLIENT_ID=""
+AUTHENTIK_CLIENT_SECRET=""
+AUTHENTIK_ISSUER=""
+AUTHENTIK_REFRESH_TOKEN_URL=""
+
+# Fief
+FIEF_CLIENT_ID=""
+FIEF_CLIENT_SECRET=""
+FIEF_URL=""
+
+# Zulip integration (optional)
+ZULIP_API_KEY=""
+ZULIP_BOT_EMAIL=""
+ZULIP_REALM=""
+
+# External services (optional)
+ZEPHYR_LLM_URL=""
+
+# Redis/KV (optional)
+KV_REST_API_TOKEN=""
+KV_REST_API_READ_ONLY_TOKEN=""
+KV_REST_API_URL=""
+KV_URL=""