feat(ws2): ADR-093 路由統一 — BIGINT + NotificationMatrix + feature flag

## 修復

### T2.1 BigInteger overflow 修復
- `db/models.py`: telegram_chat_id Integer → BigInteger
  （原 int32 無法容納群組 ID -1003711974679）

### T2.2 移除 CAST workaround
- `approval_db.py:739`: 移除 CAST(:telegram_chat_id AS BIGINT)
  ORM 已正確使用 BigInteger，workaround 可退役

### T2.3 Redis key 一致性修復
- `heartbeat_report_service.py:575`: telegram:polling_leader → telegram:polling:leader
  （telegram_gateway.py 使用冒號分隔，heartbeat 用底線是 bug）

## 新增

### T2.4 notification_matrix.py
- `services/notification_matrix.py`: ADR-093 路由矩陣
  - Destination(DM/GROUP/BOTH) + RoutingRule dataclass
  - NOTIFICATION_ROUTING dict（TYPE-1 ~ TYPE-8M 完整映射）
  - resolve_chat_ids(type, dm, group, *, tg_group_cutover=False) 灰階切流 API

### T2.5 telegram_gateway.py feature flag 保護
- line 43: 加 notification_matrix import
- line 1827-1834: TG_GROUP_CUTOVER=False 時維持舊行為
  TG_GROUP_CUTOVER=True 時解除 _interactive_types 黑名單，由矩陣控制

### T2.6 Migration SQL
- `migrations/adr093_notification_routing.sql`:
  - CREATE TABLE approval_records (telegram_chat_id BIGINT)
  - CREATE ROLE awoooi_migrator (IF NOT EXISTS)
  - 含舊環境 ALTER COLUMN int→bigint 保護

## 測試同步
- `tests/integration/setup_test_schema.sql`: telegram_chat_id BIGINT

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

apps/api/src/db/models.py

@@ -16,6 +16,7 @@ from uuid import uuid4
 
 from sqlalchemy import (
     JSON,
+    BigInteger,
     DateTime,
     Index,
     Integer,
@@ -162,9 +163,9 @@ class ApprovalRecord(Base):
         comment="Telegram message_id of the approval card sent to operator",
     )
     telegram_chat_id: Mapped[int | None] = mapped_column(
-        Integer,
+        BigInteger,
         nullable=True,
-        comment="Telegram chat_id where the approval card was sent",
+        comment="Telegram chat_id where the approval card was sent (BIGINT: 支援群組負數 ID)",
     )
 
     # B2 fix 2026-04-24 ogt + Claude Sonnet 4.6: Playbook 學習閉環斷鏈修復