debug: add connection-level diagnostics to trace database access

Enhanced diagnostics to trace database path resolution and table existence
at connection time. This will help identify if get_db_connection() is
resolving paths correctly and accessing the right database file.

Added diagnostics to:
- get_db_connection(): Show input path, resolved path, file existence, and tables found
- initialize_dev_database(): Verify tables exist after creation

This will reveal whether the path resolution is working correctly or if
there's a timing/caching issue with database file access.

api/database.py

@@ -32,15 +32,26 @@ def get_db_connection(db_path: str = "data/jobs.db") -> sqlite3.Connection:
     """
     # Resolve path based on deployment mode
     resolved_path = get_db_path(db_path)
+    print(f"🔍 DIAGNOSTIC [get_db_connection]: Input path='{db_path}', Resolved path='{resolved_path}'")
 
     # Ensure data directory exists
     db_path_obj = Path(resolved_path)
     db_path_obj.parent.mkdir(parents=True, exist_ok=True)
 
+    # Check if database file exists
+    file_exists = db_path_obj.exists()
+    print(f"🔍 DIAGNOSTIC [get_db_connection]: Database file exists: {file_exists}")
+
     conn = sqlite3.connect(resolved_path, check_same_thread=False)
     conn.execute("PRAGMA foreign_keys = ON")
     conn.row_factory = sqlite3.Row
 
+    # Verify tables exist
+    cursor = conn.cursor()
+    cursor.execute("SELECT name FROM sqlite_master WHERE type='table'")
+    tables = [row[0] for row in cursor.fetchall()]
+    print(f"🔍 DIAGNOSTIC [get_db_connection]: Tables in database: {tables}")
+
     return conn
 
 
@@ -274,6 +285,15 @@ def initialize_dev_database(db_path: str = "data/trading_dev.db") -> None:
     initialize_database(db_path)
     print(f"🔍 DIAGNOSTIC: initialize_dev_database() COMPLETED successfully")
 
+    # Verify tables were created
+    print(f"🔍 DIAGNOSTIC: Verifying tables exist in {db_path}")
+    verify_conn = sqlite3.connect(db_path)
+    verify_cursor = verify_conn.cursor()
+    verify_cursor.execute("SELECT name FROM sqlite_master WHERE type='table'")
+    tables = [row[0] for row in verify_cursor.fetchall()]
+    verify_conn.close()
+    print(f"🔍 DIAGNOSTIC: Tables found: {tables}")
+
 
 def cleanup_dev_database(db_path: str = "data/trading_dev.db", data_path: str = "./data/dev_agent_data") -> None:
     """