fix(db): use sqlite_vec.load(conn) instead of loadable_path()

loadable_path() returns a path without .dll extension on Windows,
causing vec0 extension loading to fail. Use sqlite_vec.load(conn)
which handles platform-specific paths correctly.

paperforge/memory/db.py

@@ -40,30 +40,19 @@ def ensure_vec_extension(conn: sqlite3.Connection) -> None:
 
     Enables vec0 virtual table support for vector similarity search.
     Gracefully no-ops when the extension is not installed.
-
-    Supports Python 3.12/3.13 (conn.load) and 3.14+ (conn.load_extension).
     """
     try:
+        import sqlite_vec
+
         conn.enable_load_extension(True)
-
-        # Python 3.12/3.13 API — searches system library path
         try:
-            conn.load("vec0")
-            return
-        except AttributeError:
-            pass  # conn.load removed in Python 3.14
-
-        # Python 3.14+ — use sqlite_vec convenience wrapper or direct path
-        try:
-            from sqlite_vec import loadable_path
-
-            conn.load_extension(str(loadable_path()))
-        except ImportError:
-            conn.load_extension("vec0")
-    except (sqlite3.OperationalError, AttributeError):
-        pass  # extension not available
-    finally:
-        try:
-            conn.enable_load_extension(False)
-        except AttributeError:
-            pass
+            sqlite_vec.load(conn)
+        except Exception:
+            pass  # extension not available
+        finally:
+            try:
+                conn.enable_load_extension(False)
+            except AttributeError:
+                pass
+    except ImportError:
+        pass  # sqlite_vec not installed