Fix vector_full_scan error and implement code quality improvements (#19)

Co-authored-by: Mte90 <403283+Mte90@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: Copilot

db/connection.py

@@ -0,0 +1,95 @@
+"""
+Unified database connection utilities.
+Provides consistent connection management across all database operations.
+"""
+import os
+import sqlite3
+from typing import Optional
+from contextlib import contextmanager
+from utils.logger import get_logger
+
+logger = get_logger(__name__)
+
+
+def get_db_connection(
+    db_path: str,
+    timeout: float = 30.0,
+    enable_wal: bool = True,
+    enable_vector: bool = False,
+    row_factory: bool = True
+) -> sqlite3.Connection:
+    """
+    Create a database connection with consistent configuration.
+    
+    Args:
+        db_path: Path to the SQLite database file
+        timeout: Timeout in seconds for waiting on locks (default: 30.0)
+        enable_wal: Enable Write-Ahead Logging mode (default: True)
+        enable_vector: Load sqlite-vector extension (default: False)
+        row_factory: Use sqlite3.Row factory for dict-like access (default: True)
+        
+    Returns:
+        sqlite3.Connection object configured for the specified operations
+        
+    Raises:
+        RuntimeError: If vector extension fails to load when enable_vector=True
+    """
+    # Create directory if needed
+    dirname = os.path.dirname(os.path.abspath(db_path))
+    if dirname and not os.path.isdir(dirname):
+        os.makedirs(dirname, exist_ok=True)
+    
+    # Create connection with consistent settings
+    conn = sqlite3.connect(db_path, timeout=timeout, check_same_thread=False)
+    
+    if row_factory:
+        conn.row_factory = sqlite3.Row
+    
+    # Enable WAL mode for better concurrency
+    if enable_wal:
+        try:
+            conn.execute("PRAGMA journal_mode = WAL;")
+        except Exception as e:
+            logger.warning(f"Failed to enable WAL mode: {e}")
+    
+    # Set busy timeout (milliseconds)
+    try:
+        conn.execute(f"PRAGMA busy_timeout = {int(timeout * 1000)};")
+    except Exception as e:
+        logger.warning(f"Failed to set busy_timeout: {e}")
+    
+    # Load vector extension if requested
+    if enable_vector:
+        from .vector_operations import load_sqlite_vector_extension
+        load_sqlite_vector_extension(conn)
+        logger.debug(f"Vector extension loaded for connection to {db_path}")
+    
+    return conn
+
+
+@contextmanager
+def db_connection(db_path: str, **kwargs):
+    """
+    Context manager for database connections with automatic cleanup.
+    
+    Args:
+        db_path: Path to the SQLite database file
+        **kwargs: Additional arguments passed to get_db_connection()
+        
+    Yields:
+        sqlite3.Connection object
+        
+    Example:
+        with db_connection(db_path) as conn:
+            cur = conn.cursor()
+            cur.execute("SELECT * FROM files")
+            results = cur.fetchall()
+    """
+    conn = get_db_connection(db_path, **kwargs)
+    try:
+        yield conn
+    finally:
+        try:
+            conn.close()
+        except Exception as e:
+            logger.warning(f"Error closing database connection: {e}")