feat: implement portfolio UUID migration and v1 API finalization (BAT-006, BAT-001 re-verified)

Core Changes:
- Migrate portfolio_id from string to UUID in schema and repository layer
- Update portfolio CLI commands to use name+user combination for identification
- Update HTTP API to accept portfolio_id as UUID path parameter
- Implement portfolio ownership validation in repository queries

Requirements Completed (REQ-016 to REQ-019):
- REQ-016: portfolios table UUID schema migration with data migration script
- REQ-017: CLI portfolio commands with name+user identification
- REQ-018: HTTP API portfolio path parameters and v1 asset_id UUID returns
- REQ-019: Portfolio UUID baseline documentation updates

BAT-001 Re-verification:
- REQ-004~010 marked as Implemented after verification evidence validation
- All v1 API endpoints verified with comprehensive test coverage

Documentation Updates:
- Update data-model.md with portfolio UUID structure
- Update interface-contract.md with UUID path parameters
- Update runtime-flows.md with ownership-based resolution flows
- Update project-structure.md with database layer changes
- Add migration script for portfolio UUID transition

Testing:
- Add test_portfolio_uuid.py for migration validation
- Update test_cli.py and test_portfolio_ownership.py for ownership checks

app/services/portfolio_service.py

@@ -214,11 +214,10 @@ class PortfolioService:
             active_strategy_id = strategy_set.id
         avabile_strategies = _merge_strategy_ids(active_strategy_id, payload.avabile_strategies)
         portfolio = self._repository.create_portfolio(
-            payload.portfolio_id,
+            payload.name,
             owner_user_id=owner_user_id,
             broker=payload.broker,
             status=payload.status,
-            name=payload.name or payload.symbol,
             symbol=payload.symbol,
             cash_balance=payload.cash_balance,
             asset_quantity=payload.asset_quantity,