fix(telemetry): INSERT OR IGNORE + WAL + try/except 三层防御加固

根治遥测写入主键冲突(UNIQUE constraint)和并发写锁(database is locked)
导致的异常冒泡，遥测侧信道错误不再污染 LLM 重试链。

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/unit/test_telemetry.py

@@ -104,3 +104,38 @@ async def test_record_cache_hit(recorder, db_path):
     conn.close()
 
     assert row["cache_hit"] == 1
+
+
+@pytest.mark.asyncio
+async def test_duplicate_call_id_does_not_raise(recorder, db_path):
+    """重复 call_id 写入应静默忽略（INSERT OR IGNORE），不抛异常。"""
+    kwargs = _make_call_kwargs()
+    await recorder.record_llm_call(**kwargs)
+    await recorder.record_llm_call(**kwargs)
+    conn = sqlite3.connect(str(db_path))
+    rows = conn.execute("SELECT COUNT(*) FROM llm_calls").fetchone()
+    conn.close()
+    assert rows[0] == 1
+
+
+@pytest.mark.asyncio
+async def test_db_error_does_not_propagate(tmp_path):
+    """SQLite 写入失败时 record_llm_call 应静默降级，不抛异常。"""
+    bad_recorder = SQLiteTelemetryRecorder(db_path=tmp_path / "nonexistent_dir" / "bad.db")
+    kwargs = _make_call_kwargs()
+    await bad_recorder.record_llm_call(**kwargs)
+
+
+@pytest.mark.asyncio
+async def test_concurrent_writes_no_lock_error(recorder, db_path):
+    """16 路并发 record_llm_call 应全部成功，无 database is locked 错误。"""
+    import asyncio
+    tasks = []
+    for _ in range(16):
+        kwargs = _make_call_kwargs()
+        tasks.append(recorder.record_llm_call(**kwargs))
+    await asyncio.gather(*tasks)
+    conn = sqlite3.connect(str(db_path))
+    count = conn.execute("SELECT COUNT(*) FROM llm_calls").fetchone()[0]
+    conn.close()
+    assert count == 16