feat(database): add database configuration wizard and migration tool

Add a guided database configuration wizard and a data migration tool that
allows users to:
- Build database connection strings through a step-by-step UI
- Test database connections before applying
- Preview and execute data migrations from SQLite to PostgreSQL/MySQL
- Copy to clipboard for easy .env file updates

New files:
- app/utils/db_wizard.py — connection string builder, parser, and tester
- app/utils/db_migrate.py — table-by-table data migration utility
- app/api/database.py — REST API endpoints for wizard operations
- app/views/db_wizard.py — view route for the wizard page
- frontend/templates/db_wizard.html — multi-tab wizard UI
- tests/test_db_wizard.py — unit tests for db_wizard utilities
- tests/test_db_migrate.py — unit tests for db_migrate utilities
- tests/test_db_wizard_api.py — integration tests for API and views

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/views/db_wizard.py

@@ -0,0 +1,28 @@
+"""
+Database configuration wizard view.
+
+Serves the guided UI for configuring a database connection string
+and migrating data from one database to another.
+"""
+
+import logging
+
+from fastapi import Request
+
+from app.config import settings
+from app.views.base import APIRouter, templates
+
+logger = logging.getLogger(__name__)
+router = APIRouter()
+
+
+@router.get("/database-wizard")
+async def database_wizard(request: Request) -> templates.TemplateResponse:
+    """Render the database configuration wizard page."""
+    return templates.TemplateResponse(
+        "db_wizard.html",
+        {
+            "request": request,
+            "current_database_url": settings.database_url,
+        },
+    )