fix(filesystem): preserve sqlite catalog durability

Remove the synchronous=OFF pragma from PIFS catalog inserts so SQLite remains the durable source of truth.

tests/test_filesystem_store.py

@@ -0,0 +1,45 @@
+import json
+
+
+def test_insert_files_does_not_disable_sqlite_synchronous(tmp_path):
+    from pageindex.filesystem.store import SQLiteFileSystemStore
+
+    statements = []
+
+    class RecordingStore(SQLiteFileSystemStore):
+        def connect(self):
+            conn = super().connect()
+            conn.set_trace_callback(statements.append)
+            return conn
+
+    store = RecordingStore(tmp_path / "workspace")
+    statements.clear()
+
+    store.insert_files(
+        [
+            {
+                "file_ref": "ref_report",
+                "external_id": "doc_report",
+                "storage_uri": "file:///tmp/report.pdf",
+                "source_path": "documents/report.pdf",
+                "folder_path": "/documents",
+                "title": "Report",
+                "descriptor": "documents/report.pdf",
+                "content_type": "application/pdf",
+                "source_type": "documents",
+                "fingerprint": "fingerprint",
+                "text_artifact_path": "artifacts/text/ref_report.txt",
+                "raw_artifact_path": None,
+                "metadata": {},
+                "metadata_json": json.dumps({}),
+                "metadata_text": "",
+                "content": "",
+                "skip_fts": True,
+            }
+        ]
+    )
+
+    assert not any(
+        statement.upper().replace(" ", "") == "PRAGMASYNCHRONOUS=OFF"
+        for statement in statements
+    )