feat: refactor User/Bot architecture and implement multi-channel gateway

Major changes:
1. Core Architecture: Decoupled Bots from Users. Bots now have independent lifecycles, member management (bot_members), and dedicated configurations.
2. Channel Gateway:
   - Implemented a unified Channel Manager supporting Feishu, Telegram, and Local (Web/CLI) adapters.
   - Added message processing pipeline to normalize interactions across different platforms.
   - Introduced a Contact system for identity binding and guest access policies.
3. Database & Tooling:
   - Consolidated all migrations into 0001_init with updated schema for bots, channels, and contacts.
   - Optimized sqlc.yaml to automatically track the migrations directory.
4. Agent Enhancements:
   - Introduced ToolContext to provide Agents with platform-aware execution capabilities (e.g., messaging, contact lookups).
   - Added tool logging and fallback mechanisms for toolChoice execution.
5. UI & Docs: Updated frontend stores, UI components, and Swagger documentation to align with the new Bot-centric model.

internal/settings/types.go

@@ -11,6 +11,7 @@ type Settings struct {
 	EmbeddingModelID   string `json:"embedding_model_id"`
 	MaxContextLoadTime int    `json:"max_context_load_time"`
 	Language           string `json:"language"`
+	AllowGuest         bool   `json:"allow_guest"`
 }
 
 type UpsertRequest struct {
@@ -19,4 +20,5 @@ type UpsertRequest struct {
 	EmbeddingModelID   string `json:"embedding_model_id,omitempty"`
 	MaxContextLoadTime *int   `json:"max_context_load_time,omitempty"`
 	Language           string `json:"language,omitempty"`
+	AllowGuest         *bool  `json:"allow_guest,omitempty"`
 }