Fix SQLite WAL mode error on FUSE filesystems

WAL mode can fail on filesystems like mergerfs that don't fully support
memory-mapped files. Add graceful fallback to DELETE journal mode.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/smarttools/registry/db.py

@@ -245,7 +245,13 @@ def connect_db(path: Path | None = None) -> sqlite3.Connection:
     ensure_db_directory(db_path)
     conn = sqlite3.connect(db_path)
     conn.row_factory = sqlite3.Row
-    conn.execute("PRAGMA journal_mode=WAL;")
+    # WAL mode provides better concurrency but may not work on all filesystems
+    # (e.g., some FUSE filesystems like mergerfs). Fall back gracefully.
+    try:
+        conn.execute("PRAGMA journal_mode=WAL;")
+    except sqlite3.OperationalError:
+        # Fall back to DELETE journal mode which works everywhere
+        conn.execute("PRAGMA journal_mode=DELETE;")
     conn.execute("PRAGMA foreign_keys=ON;")
     return conn