feat(REQ-001): add portfolio comment history API, CLI, repository, migration, and tests

Agent-Logs-Url: https://github.com/genichin/portfolio-hub/sessions/64fc2cec-78f5-41d1-99a4-45f868781edd

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

app/repositories/portfolio_repository.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 from datetime import datetime
 from typing import Protocol
 
-from app.domain.models import AuthToken, BotPrincipal, LedgerEntry, Portfolio, StrategySet, TokenPrincipal, User
+from app.domain.models import AuthToken, BotPrincipal, LedgerEntry, Portfolio, PortfolioComment, StrategySet, TokenPrincipal, User
 
 
 class PortfolioRepository(Protocol):
@@ -147,3 +147,11 @@ class PortfolioRepository(Protocol):
 
     def delete(self, portfolio_id: str, *, clear_ledger: bool = True) -> None: ...
 
+    def create_comment(self, portfolio_id: str, *, content: str) -> PortfolioComment: ...
+
+    def list_comments(self, portfolio_id: str) -> list[PortfolioComment]: ...
+
+    def update_comment(self, portfolio_id: str, comment_id: str, *, content: str) -> PortfolioComment: ...
+
+    def delete_comment(self, portfolio_id: str, comment_id: str) -> None: ...
+