feat(req-002): implement portfolio tagging and tag filters

app/schemas/portfolio.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 from datetime import datetime
 from typing import Any, Literal
 
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, ConfigDict, Field, field_validator
 
 
 class StrategySetResponse(BaseModel):
@@ -45,6 +45,7 @@ class PortfolioSummary(BaseModel):
     status: str
     name: str
     symbol: str
+    tags: list[str] = Field(default_factory=list)
     owner_user_id: str | None = None
     cash_balance: float = 0.0
     asset_quantity: float = 0.0
@@ -140,6 +141,24 @@ class CommentResponse(BaseModel):
     updated_at: datetime | None = None
 
 
+class PortfolioTagMutationRequest(BaseModel):
+    tag: str = Field(min_length=1)
+
+    @field_validator("tag")
+    @classmethod
+    def normalize_tag(cls, value: str) -> str:
+        normalized = value.strip()
+        if not normalized:
+            raise ValueError("tag는 비어 있을 수 없습니다")
+        return normalized
+
+
+class PortfolioTagResponse(BaseModel):
+    portfolio_id: str
+    tag: str
+    created_at: datetime | None = None
+
+
 class ErrorResponse(BaseModel):
     detail: str
     model_config = ConfigDict(extra="ignore")