fix: Edge队列时间戳根治 — INSERT显式北京时间 + 存量表schema迁移

795e8ac 只改了 CREATE TABLE 的 DEFAULT，但 DEFAULT 固化在已存在表的
schema 中，IF NOT EXISTS 不会更新旧表——新行 created_at 仍走旧
DEFAULT(localtime)=UTC。三处修复:
1. enqueue INSERT 显式写 created_at/updated_at (+8 hours)，不再依赖 schema DEFAULT
2. _init_db 检测旧 schema 含 localtime 时重建表迁移（数据保留，幂等）
3. 存量数据修正: 行16/19 created_at +8h

验证: 本地迁移单测3例通过；线上行20(task 44) created_at=18:43:35
为北京时间(UTC机器当时10:43)。

fam-edge/src/fam_edge/queue/queue_manager.py

@@ -30,11 +30,8 @@ def _get_conn() -> sqlite3.Connection:
     return conn
 
 
-def _init_db():
-    os.makedirs(os.path.dirname(DB_PATH), exist_ok=True)
-    conn = sqlite3.connect(DB_PATH)
-    conn.execute("""
-        CREATE TABLE IF NOT EXISTS task_queue (
+_TASK_QUEUE_DDL = """
+    CREATE TABLE {name} (
         id INTEGER PRIMARY KEY AUTOINCREMENT,
         nas_task_id INTEGER NOT NULL,
         video_filename TEXT NOT NULL,
@@ -52,7 +49,26 @@ def _init_db():
         delivered INTEGER DEFAULT 0,
         UNIQUE(nas_task_id)
     )
-    """)
+"""
+
+
+def _init_db():
+    os.makedirs(os.path.dirname(DB_PATH), exist_ok=True)
+    conn = sqlite3.connect(DB_PATH)
+    # DEFAULT 约束固化在表 schema 中，CREATE TABLE IF NOT EXISTS 不会更新已存在的旧表
+    # （旧表 DEFAULT 是 localtime，UTC 机器上=UTC）。检测到旧 schema 时重建表迁移。
+    row = conn.execute(
+        "SELECT sql FROM sqlite_master WHERE type='table' AND name='task_queue'"
+    ).fetchone()
+    if row is not None and 'localtime' in (row[0] or ''):
+        conn.execute("BEGIN IMMEDIATE")
+        conn.execute(_TASK_QUEUE_DDL.format(name='task_queue_new'))
+        conn.execute("INSERT INTO task_queue_new SELECT * FROM task_queue")
+        conn.execute("DROP TABLE task_queue")
+        conn.execute("ALTER TABLE task_queue_new RENAME TO task_queue")
+        conn.commit()
+    conn.execute(_TASK_QUEUE_DDL.format(name='task_queue').replace(
+        'CREATE TABLE task_queue', 'CREATE TABLE IF NOT EXISTS task_queue'))
     conn.execute("CREATE INDEX IF NOT EXISTS idx_status ON task_queue(status)")
     conn.execute("CREATE INDEX IF NOT EXISTS idx_delivered ON task_queue(delivered)")
     conn.commit()
@@ -66,8 +82,9 @@ def enqueue(nas_task_id: int, video_filename: str, video_path: str,
     try:
         cur = conn.execute(
             "INSERT OR IGNORE INTO task_queue "
-            "(nas_task_id, video_filename, video_path, camera_name, event_start_time, known_members_context) "
-            "VALUES (?, ?, ?, ?, ?, ?)",
+            "(nas_task_id, video_filename, video_path, camera_name, event_start_time, "
+            "known_members_context, created_at, updated_at) "
+            "VALUES (?, ?, ?, ?, ?, ?, datetime('now','+8 hours'), datetime('now','+8 hours'))",
             (nas_task_id, video_filename, video_path, camera_name, event_start_time, known_members_context)
         )
         conn.commit()