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/domain/services.py

@@ -39,12 +39,11 @@ class PortfolioDomainRepository(Protocol):
     ) -> Portfolio: ...
     def create_portfolio(
         self,
-        portfolio_id: str,
+        name: str,
         *,
         owner_user_id: str,
         broker: str,
         status: str,
-        name: str,
         symbol: str,
         cash_balance: float,
         asset_quantity: float,
@@ -53,6 +52,7 @@ class PortfolioDomainRepository(Protocol):
         active_strategy_id: str | None,
         avabile_strategies: list[str] | None,
     ) -> Portfolio: ...
+    def get_portfolio_by_name_and_user(self, owner_user_id: str, name: str) -> Portfolio | None: ...
     def update_portfolio(self, portfolio_id: str, **fields: object) -> Portfolio: ...
     def list_portfolios(
         self,