music(chord): 加 yopu.co 吉他谱自动抓取（sidecar 模式）

复刻 ../guitar 的功能：
- 新加 chord-fetcher sidecar（python 3.11 + chromium + selenium），跟 main 同 pod 共享 PVC
- yopu.py v2：搜「和弦谱」→ 进 view → 选 谱面样式=功能谱 + 和弦样式=级数名 → 截 sheet-container → PIL 裁白边
- music backend 加 POST /api/pieces/:id/chord/fetch + GET /chord/status，转发 sidecar 并把 png import 成 image attachment role=chord
- 前端 chord tab 在没图时显示「自动抓取」按钮，点了 polling 状态、完成后刷新
- CI build 两个 image（music + music-chord），rollout 同步切版本

apps/music/chord/chord_server.py

@@ -0,0 +1,127 @@
+"""
+chord-fetcher sidecar 的 HTTP service。
+
+跟 music 主容器同 pod，监听 :8001。被 music backend 通过 localhost 调用。
+worker 单线程串行（chromium 一次跑一个，省资源），文件落 /data/chord-fetch/{piece_id}.png。
+"""
+
+import json
+import logging
+import queue
+import threading
+import os
+from pathlib import Path
+from typing import Optional
+
+from fastapi import FastAPI, HTTPException
+from fastapi.responses import FileResponse
+
+import yopu
+
+logging.basicConfig(level=logging.INFO,
+                    format='%(asctime)s %(levelname)s %(name)s: %(message)s')
+logger = logging.getLogger('chord-server')
+
+OUT_DIR = Path(os.getenv('CHORD_OUT_DIR', '/data/chord-fetch'))
+OUT_DIR.mkdir(parents=True, exist_ok=True)
+
+app = FastAPI()
+
+
+# in-memory job state. piece_id -> {status, error, query}
+state: dict[int, dict] = {}
+state_lock = threading.Lock()
+job_q: queue.Queue = queue.Queue()
+
+
+def out_path(piece_id: int) -> Path:
+    return OUT_DIR / f"{piece_id}.png"
+
+
+def worker():
+    while True:
+        piece_id, query = job_q.get()
+        with state_lock:
+            state[piece_id] = {'status': 'processing', 'error': '', 'query': query}
+        logger.info("[piece=%d] start fetch query=%r", piece_id, query)
+        try:
+            ok, msg = yopu.fetch_chord_chart(query, str(out_path(piece_id)))
+            with state_lock:
+                if ok:
+                    state[piece_id] = {'status': 'completed', 'error': '', 'query': query}
+                    logger.info("[piece=%d] completed: %s", piece_id, msg)
+                else:
+                    state[piece_id] = {'status': 'failed', 'error': msg, 'query': query}
+                    logger.warning("[piece=%d] failed: %s", piece_id, msg)
+        except Exception as e:
+            logger.exception("[piece=%d] worker crash", piece_id)
+            with state_lock:
+                state[piece_id] = {'status': 'failed', 'error': str(e), 'query': query}
+        finally:
+            job_q.task_done()
+
+
+threading.Thread(target=worker, daemon=True).start()
+
+
+@app.get('/healthz')
+def healthz():
+    return {'ok': True}
+
+
+@app.post('/fetch')
+def fetch(piece_id: int, query: str):
+    """加入 fetch 队列。query 一般是 '<artist> <title>'。
+    幂等：已 completed 且文件还在，直接返回 completed。"""
+    if piece_id <= 0 or not query.strip():
+        raise HTTPException(400, 'piece_id / query required')
+
+    with state_lock:
+        cur = state.get(piece_id, {})
+        if cur.get('status') == 'completed' and out_path(piece_id).exists():
+            return {'status': 'completed'}
+        if cur.get('status') in ('pending', 'processing'):
+            return {'status': cur['status']}
+        state[piece_id] = {'status': 'pending', 'error': '', 'query': query}
+
+    job_q.put((piece_id, query))
+    return {'status': 'pending'}
+
+
+@app.get('/status/{piece_id}')
+def status(piece_id: int):
+    with state_lock:
+        cur = state.get(piece_id, {})
+    file_exists = out_path(piece_id).exists()
+    if cur.get('status') == 'completed' and not file_exists:
+        return {'status': 'failed', 'error': 'png 文件丢了'}
+    if not cur and file_exists:
+        return {'status': 'completed'}
+    return {
+        'status': cur.get('status', 'none'),
+        'error': cur.get('error', ''),
+        'query': cur.get('query', ''),
+        'file_exists': file_exists,
+    }
+
+
+@app.get('/image/{piece_id}')
+def image(piece_id: int):
+    p = out_path(piece_id)
+    if not p.exists():
+        raise HTTPException(404, 'not found')
+    return FileResponse(p, media_type='image/png')
+
+
+@app.delete('/state/{piece_id}')
+def reset(piece_id: int):
+    """music backend import 完后清状态 + 删 png（防 PVC 越积越多）。"""
+    with state_lock:
+        state.pop(piece_id, None)
+    p = out_path(piece_id)
+    if p.exists():
+        try:
+            p.unlink()
+        except Exception as e:
+            logger.warning("[piece=%d] cleanup unlink: %s", piece_id, e)
+    return {'ok': True}