refactor(db): unify SQLite table schema management and initialization (#310)

Centralized all 11 Hermes SQLite table definitions and initialization logic
into a single schemas.ts file to eliminate duplication and improve maintainability.

Changes:
- **NEW**: packages/server/src/db/hermes/schemas.ts
  - Centralized schema definitions for all 11 tables
  - Unified initAllHermesTables() function with migration logic
  - Includes usage table PRIMARY KEY migration (session_id → id)

- **Refactored**: packages/server/src/db/hermes/init.ts
  - Simplified from async to sync (all operations are synchronous)
  - Single responsibility: delegate to schemas.ts

- **Refactored**: packages/server/src/db/hermes/session-store.ts
  - Removed schema definitions (now in schemas.ts)
  - Removed initSessionStore() function
  - Imports table constants from schemas.ts

- **Refactored**: packages/server/src/db/hermes/usage-store.ts
  - Removed initUsageStore() function and migration logic
  - Migration moved to schemas.ts for consistency
  - Only handles CRUD operations now

- **Refactored**: packages/server/src/db/hermes/compression-snapshot.ts
  - Removed initCompressionSnapshotStore() function
  - Fixed duplicate getCompressionSnapshot definition
  - Imports table constant from schemas.ts

- **Refactored**: packages/server/src/services/hermes/group-chat/index.ts
  - Removed ensureTable() calls (now in schemas.ts)
  - Only handles index creation now
  - Imports table constants from schemas.ts

- **Updated**: packages/server/src/index.ts
  - Removed await from initAllStores() call (now sync)

Benefits:
- 🎯 Single responsibility: schemas.ts manages all tables, stores only do CRUD
- 📋 Centralized maintenance: all table definitions in one place
- 🔄 No duplication: each table created exactly once with proper migrations
- 🚀 Clean architecture: clear separation between initialization and operations

Tables managed (11 total):
1. session_usage (usage statistics)
2. sessions (session metadata)
3. messages (message content)
4. chat_compression_snapshots (compression snapshots)
5. gc_rooms (group chat rooms)
6. gc_messages (group chat messages)
7. gc_room_agents (room agents)
8. gc_context_snapshots (group chat snapshots)
9. gc_room_members (room members)
10. gc_pending_session_deletes (pending session deletes)
11. gc_session_profiles (session profiles)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/server/src/db/hermes/session-store.ts

@@ -2,7 +2,8 @@
  * Self-built session database — completely replaces Hermes CLI dependency.
  * Uses the same ensureTable/getDb pattern as usage-store.ts.
  */
-import { isSqliteAvailable, ensureTable, getDb } from '../index'
+import { isSqliteAvailable, getDb } from '../index'
+import { SESSIONS_TABLE, MESSAGES_TABLE } from './schemas'
 
 // Re-export types for compatibility with sessions-db.ts consumers
 export interface HermesSessionRow {
@@ -57,65 +58,8 @@ export interface HermesSessionDetailRow extends HermesSessionRow {
   thread_session_count: number
 }
 
-// --- Schema ---
-
-const SESSIONS_TABLE = 'sessions'
-
-const SESSIONS_SCHEMA: Record<string, string> = {
-  id: 'TEXT PRIMARY KEY',
-  profile: 'TEXT NOT NULL DEFAULT \'default\'',
-  source: 'TEXT NOT NULL DEFAULT \'api_server\'',
-  user_id: 'TEXT',
-  model: 'TEXT NOT NULL DEFAULT \'\'',
-  title: 'TEXT',
-  started_at: 'INTEGER NOT NULL',
-  ended_at: 'INTEGER',
-  end_reason: 'TEXT',
-  message_count: 'INTEGER NOT NULL DEFAULT 0',
-  tool_call_count: 'INTEGER NOT NULL DEFAULT 0',
-  input_tokens: 'INTEGER NOT NULL DEFAULT 0',
-  output_tokens: 'INTEGER NOT NULL DEFAULT 0',
-  cache_read_tokens: 'INTEGER NOT NULL DEFAULT 0',
-  cache_write_tokens: 'INTEGER NOT NULL DEFAULT 0',
-  reasoning_tokens: 'INTEGER NOT NULL DEFAULT 0',
-  billing_provider: 'TEXT',
-  estimated_cost_usd: 'REAL NOT NULL DEFAULT 0',
-  actual_cost_usd: 'REAL',
-  cost_status: 'TEXT NOT NULL DEFAULT \'\'',
-  preview: 'TEXT NOT NULL DEFAULT \'\'',
-  last_active: 'INTEGER NOT NULL',
-}
-
-const MESSAGES_TABLE = 'messages'
-
-const MESSAGES_SCHEMA: Record<string, string> = {
-  id: 'INTEGER PRIMARY KEY AUTOINCREMENT',
-  session_id: 'TEXT NOT NULL',
-  role: 'TEXT NOT NULL',
-  content: 'TEXT NOT NULL DEFAULT \'\'',
-  tool_call_id: 'TEXT',
-  tool_calls: 'TEXT',
-  tool_name: 'TEXT',
-  timestamp: 'INTEGER NOT NULL',
-  token_count: 'INTEGER',
-  finish_reason: 'TEXT',
-  reasoning: 'TEXT',
-  reasoning_details: 'TEXT',
-  reasoning_content: 'TEXT',
-  codex_reasoning_items: 'TEXT',
-}
-
-const MESSAGES_INDEX = 'CREATE INDEX IF NOT EXISTS idx_messages_session_id ON messages(session_id)'
-
-// --- Init ---
-
-export function initSessionStore(): void {
-  if (!isSqliteAvailable()) return
-  ensureTable(SESSIONS_TABLE, SESSIONS_SCHEMA)
-  ensureTable(MESSAGES_TABLE, MESSAGES_SCHEMA)
-  const db = getDb()!
-  db.exec(MESSAGES_INDEX)
-}
+// Note: Table schemas and initialization are now centralized in schemas.ts
+// Tables are created automatically on bootstrap via initAllHermesTables()
 
 // --- Helpers ---