feat(console): add integration tests and polish error handling

Add MockRenderer-based integration tests that verify the full screen-to-
renderer pipeline without a real terminal. Update main.py with proper
--db flag handling, database existence check, startup banner, and
graceful error handling.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

console/main.py

@@ -8,6 +8,7 @@ Usage:
 """
 
 import argparse
+import os
 import sys
 
 from console.config import VERSION, APP_NAME, APP_SUBTITLE, DB_PATH, DEFAULT_MODE
@@ -38,6 +39,19 @@ def parse_args(argv=None):
     return parser.parse_args(argv)
 
 
+def _print_banner(mode, db_path):
+    """Print a startup banner before entering terminal mode."""
+    border = "=" * 58
+    print(border)
+    print(f"  {APP_NAME} v{VERSION}")
+    print(f"  {APP_SUBTITLE}")
+    print(border)
+    print(f"  Mode : {mode}")
+    print(f"  DB   : {db_path}")
+    print(border)
+    print()
+
+
 def main(argv=None):
     """Main entry point: parse args, set up renderer, DB, and launch the app."""
     args = parse_args(argv)
@@ -45,20 +59,60 @@ def main(argv=None):
     db_path = args.db
     mode = args.mode
 
+    # Verify the database file exists before proceeding
+    if not os.path.isfile(db_path):
+        print(
+            f"Error: Database not found at '{db_path}'.\n"
+            f"\n"
+            f"Make sure the vehicle database exists.  You can specify a\n"
+            f"custom path with the --db flag:\n"
+            f"\n"
+            f"    python -m console --db /path/to/vehicle_database.db\n",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+
     # Lazy imports so the module can be loaded without curses available
     # (e.g. during tests or when just checking --version).
-    from console.core.database import Database
-    from console.renderers import create_renderer
+    from console.db import Database
+    from console.renderers.curses_renderer import CursesRenderer
     from console.core.app import App
 
+    # Print startup banner
+    _print_banner(mode, db_path)
+
     db = Database(db_path)
-    renderer = create_renderer(mode)
+
+    # Select renderer based on mode
+    if mode == "modern":
+        try:
+            from console.renderers.textual_renderer import TextualRenderer
+            renderer = TextualRenderer()
+        except ImportError:
+            print(
+                "Warning: 'modern' mode requires the 'rich' package.\n"
+                "Falling back to vt220 mode.\n"
+                "Install with: pip install rich\n",
+                file=sys.stderr,
+            )
+            renderer = CursesRenderer()
+    else:
+        renderer = CursesRenderer()
+
     app = App(renderer=renderer, db=db)
 
     try:
         app.run()
-    finally:
-        db.close()
+    except KeyboardInterrupt:
+        pass
+    except Exception as e:
+        # Ensure terminal is restored before printing the traceback
+        try:
+            renderer.cleanup()
+        except Exception:
+            pass
+        print(f"\nError: {e}", file=sys.stderr)
+        sys.exit(1)
 
 
 if __name__ == "__main__":