fix: SQLite 'database is locked' by adding busy timeout (#6474)

The async engine is created without a busy timeout, so concurrent
writes (agent responses, metrics, session updates) fail instantly
with 'database is locked' instead of waiting for the lock.

Add connect_args={'timeout': 30} for SQLite engines so the driver
waits up to 30 seconds for the write lock. Combined with the existing
WAL journal mode, this handles the typical concurrent write bursts
from agent + metrics + session operations.

Fixes #6443

astrbot/core/db/__init__.py

@@ -33,10 +33,18 @@ class BaseDatabase(abc.ABC):
     DATABASE_URL = ""
 
     def __init__(self) -> None:
+        # SQLite only supports a single writer at a time.  Without a busy
+        # timeout the driver raises "database is locked" instantly when a
+        # second write is attempted.  Setting timeout=30 tells SQLite to
+        # wait up to 30 s for the lock, which is enough to ride out brief
+        # write bursts from concurrent agent/metrics/session operations.
+        is_sqlite = "sqlite" in self.DATABASE_URL
+        connect_args = {"timeout": 30} if is_sqlite else {}
         self.engine = create_async_engine(
             self.DATABASE_URL,
             echo=False,
             future=True,
+            connect_args=connect_args,
         )
         self.AsyncSessionLocal = async_sessionmaker(
             self.engine,