refactor: remove standalone mode, consolidate to managed-only (PostgreSQL) (#70)

- Remove standalone mode code: file-based stores, standalone gateway,
  heartbeat service, SQLite memory, standalone docker-compose
- Rename docker-compose.managed.yml → docker-compose.postgres.yml
- Clean up ~130 Go comments referencing "managed mode" qualifier
- Simplify docker-compose.yml env vars (providers/channels via web UI)
- Update .env.example to essential vars only (token + encryption key)
- Add setup wizard UI (provider → agent → channel bootstrap flow)
- Add logs.tail WebSocket handler for live log streaming
- Add cursor-pointer to interactive UI components
- Clean up config page (remove standalone-only sections)
- Update README and docs for managed-only architecture

.env.example

@@ -1,38 +1,13 @@
 # GoClaw environment variables.
 # Copy to .env and fill in values. For Docker Compose, do NOT use 'export' prefix.
 #
-# Required: at least one LLM provider API key.
 # Auto-generated by prepare-env.sh: GOCLAW_GATEWAY_TOKEN, GOCLAW_ENCRYPTION_KEY.
+# LLM providers and channels are configured via the web dashboard setup wizard.
 
-# --- LLM Provider (at least one API key required) ---
-# Provider is auto-detected from API keys. Default model is chosen per provider.
-# GOCLAW_MODEL=                  # Optional: override default model
-GOCLAW_OPENROUTER_API_KEY=
-GOCLAW_ANTHROPIC_API_KEY=
-GOCLAW_OPENAI_API_KEY=
-GOCLAW_MINIMAX_API_KEY=
-GOCLAW_GROQ_API_KEY=
-GOCLAW_DEEPSEEK_API_KEY=
-GOCLAW_GEMINI_API_KEY=
-GOCLAW_MISTRAL_API_KEY=
-GOCLAW_XAI_API_KEY=
-GOCLAW_COHERE_API_KEY=
-GOCLAW_PERPLEXITY_API_KEY=
-
-# --- Gateway ---
+# --- Gateway (required) ---
 GOCLAW_GATEWAY_TOKEN=
 GOCLAW_ENCRYPTION_KEY=
 
-# --- Channels (optional) ---
-GOCLAW_TELEGRAM_TOKEN=
-GOCLAW_DISCORD_TOKEN=
-GOCLAW_LARK_APP_ID=
-GOCLAW_LARK_APP_SECRET=
-# GOCLAW_LARK_ENCRYPT_KEY=
-# GOCLAW_LARK_VERIFICATION_TOKEN=
-GOCLAW_ZALO_TOKEN=
-# GOCLAW_WHATSAPP_BRIDGE_URL=
-
 # --- Database (only for non-Docker deployments) ---
 # Docker Compose auto-builds this from POSTGRES_USER/PASSWORD/DB.
 # GOCLAW_POSTGRES_DSN=postgres://user:pass@host:5432/dbname?sslmode=disable