feat(REQ-014): add portfolio-create-user-required requirement and implementation

- Add docs/srs/Interface/req-014_portfolio-create-user-required.md with acceptance criteria
- Create docs/batches/bat-004_20260502_portfolio-create-user-required/ delivery batch
- Enhance app/cli/commands/portfolio.py: validate user_id parameter before portfolio creation
- Add comprehensive CLI tests in tests/test_cli.py for portfolio create validation flows
- Update docs/batches/index.md and docs/srs/index.md with new requirement/batch references
- Update README.md documentation

app/cli/commands/portfolio.py

@@ -119,6 +119,7 @@ def portfolio_status(
 def create_portfolio(
     ctx: typer.Context,
     portfolio_id: str = typer.Argument(..., help="Portfolio identifier."),
+    user: str | None = typer.Option(None, "--user", help="Owner username (required)."),
     name: str | None = typer.Option(None, help="Asset display name."),
     symbol: str = typer.Option(..., help="Trading symbol."),
     broker: str = typer.Option("kis", help="Broker code."),
@@ -131,10 +132,16 @@ def create_portfolio(
     strategy_params: str = typer.Option("{}", help="Strategy params as JSON object."),
     force: bool = typer.Option(False, "--force", help="Skip confirmation prompt."),
 ) -> None:
+    if user is None:
+        ctx.obj.console.print("Error: --user 옵션은 필수입니다.")
+        raise typer.Exit(code=1)
     _confirm(force, f"Create portfolio {portfolio_id} for symbol {symbol}?")
-    detail = _with_service(
-        ctx,
-        lambda service, app_context: service.create_portfolio(
+
+    def _callback(service, repository, app_context):
+        owner = repository.get_user_by_username(user)
+        if owner is None:
+            raise ValueError(f"사용자를 찾을 수 없습니다: {user}")
+        return service.create_portfolio(
             CreatePortfolioRequest(
                 portfolio_id=portfolio_id,
                 name=name,
@@ -147,9 +154,11 @@ def create_portfolio(
                 profit_buffer=profit_buffer,
                 strategy_name=strategy_name,
                 strategy_params=_parse_strategy_params(strategy_params),
-            )
-        ),
-    )
+            ),
+            owner_user_id=owner.id,
+        )
+
+    detail = _with_service_and_repo(ctx, _callback)
     render_output(ctx.obj.console, ctx.obj.output_format, detail)