feat(phase-5): FastAPI 엔드포인트 (검색/차트/예측/메트릭/뉴스)

- GET  /api/symbols/search?q=...&seed_only=  : trigram + prefix + ILIKE 합산 정렬
- GET  /api/symbols/{code}                    : 메타
- GET  /api/chart/{code}?days=N&include_*     : OHLCV + 일별 감성 + 외인기관거래대금
- POST /api/predict/{code}?horizons=1,3,5     : on-demand 앙상블 예측 + DB 적재
                                                (user_triggered=TRUE)
- GET  /api/predict/{code}/latest             : 최신 base_date 의 예측 묶음 + base_close
                                                (UI 가 차트 마지막 점에 이어 붙임)
- GET  /api/metrics/{code}?window_days=N      : 종목 단위 hit_rate / mae (model, horizon 별)
- GET  /api/metrics?window_days=N             : 전체 누적
- GET  /api/news/{code}?source=&limit=        : 최신순 뉴스/공시 목록 (감성 점수 포함)

main.py 에 6개 라우터 모두 include.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/app/api/symbols.py

@@ -0,0 +1,101 @@
+"""종목 검색 / 메타 API."""
+from __future__ import annotations
+
+from fastapi import APIRouter, HTTPException, Query
+from sqlalchemy import text
+
+from app.db.connection import get_engine
+
+router = APIRouter(prefix="/api/symbols", tags=["symbols"])
+
+
+@router.get("/search")
+def search_symbols(
+    q: str = Query(..., min_length=1, max_length=40, description="종목명 또는 코드 prefix/부분 일치"),
+    limit: int = Query(default=20, ge=1, le=100),
+    seed_only: bool = Query(default=False, description="true 면 학습/배치 대상 10종목만"),
+) -> dict:
+    """이름은 trigram + ILIKE, 코드는 prefix 매치.
+
+    우선순위:
+      1) 코드가 정확히 같으면 가장 위
+      2) 이름 prefix 매치
+      3) 이름 부분 매치 (trigram similarity)
+    """
+    q_norm = q.strip()
+    if not q_norm:
+        raise HTTPException(status_code=400, detail="empty query")
+
+    eng = get_engine()
+    where_seed = "AND is_seed = TRUE" if seed_only else ""
+    sql = text(
+        f"""
+        WITH ranked AS (
+          SELECT code, name, market, sector, is_seed,
+            CASE
+              WHEN code = :q                          THEN 0
+              WHEN code LIKE :prefix                  THEN 1
+              WHEN name LIKE :prefix                  THEN 2
+              WHEN name ILIKE :contains               THEN 3
+              ELSE 4
+            END AS rank,
+            similarity(name, :q) AS sim
+            FROM symbols
+           WHERE active = TRUE
+             {where_seed}
+             AND (code LIKE :prefix OR name ILIKE :contains OR similarity(name, :q) > 0.2)
+        )
+        SELECT code, name, market, sector, is_seed
+          FROM ranked
+         ORDER BY rank ASC, sim DESC, name ASC
+         LIMIT :lim
+        """
+    )
+    with eng.connect() as conn:
+        rows = conn.execute(
+            sql,
+            {
+                "q": q_norm,
+                "prefix": f"{q_norm}%",
+                "contains": f"%{q_norm}%",
+                "lim": limit,
+            },
+        ).all()
+    return {
+        "q": q_norm,
+        "count": len(rows),
+        "items": [
+            {
+                "code": r[0],
+                "name": r[1],
+                "market": r[2],
+                "sector": r[3],
+                "is_seed": bool(r[4]),
+            }
+            for r in rows
+        ],
+    }
+
+
+@router.get("/{code}")
+def get_symbol(code: str) -> dict:
+    eng = get_engine()
+    with eng.connect() as conn:
+        row = conn.execute(
+            text(
+                "SELECT code, name, market, sector, is_seed, active, created_at "
+                "FROM symbols WHERE code = :c"
+            ),
+            {"c": code},
+        ).first()
+    if not row:
+        raise HTTPException(status_code=404, detail=f"unknown code: {code}")
+    return {
+        "code": row[0],
+        "name": row[1],
+        "market": row[2],
+        "sector": row[3],
+        "is_seed": bool(row[4]),
+        "active": bool(row[5]),
+        "created_at": str(row[6]) if row[6] else None,
+    }