refactor(cache): 統一 cache SOT 並啟用 gunicorn preload

ADR-017 Phase 3f-2：新增 services/cache_manager.py，讓 sales/import/export/daily/dashboard 共用同一份 in-memory cache；cache_service 改為相容 shim；Dockerfile/docker-compose 啟用 gunicorn --preload。

services/cache_manager.py

@@ -0,0 +1,125 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+快取單一來源模組。
+
+ADR-017 Phase 3f-2: 將 sales/import/export/daily 會共同碰到的
+module-level cache 收斂到這裡，避免各 route 各自持有一份 dict。
+"""
+
+import time
+
+
+class FingerprintCache:
+    """TTL + fingerprint 的小型 in-memory cache。"""
+
+    def __init__(self, name, fingerprint_fn):
+        self.name = name
+        self._store = {}
+        self._fp_fn = fingerprint_fn
+
+    def get(self, key, ttl=300):
+        entry = self._store.get(key)
+        if not entry:
+            return None
+        if time.time() - entry['ts'] > ttl:
+            return None
+        try:
+            if self._fp_fn() != entry['fp']:
+                return None
+        except Exception:
+            pass
+        return entry['data']
+
+    def set(self, key, data):
+        try:
+            fp = self._fp_fn()
+        except Exception:
+            fp = None
+        self._store[key] = {'data': data, 'ts': time.time(), 'fp': fp}
+
+    def clear(self):
+        self._store.clear()
+
+
+_SALES_DF_CACHE = {}
+_SALES_PROCESSED_CACHE = {}
+_SALES_OPTIONS_CACHE = {}
+_SALES_ANALYSIS_RESULT_CACHE = {}
+_SALES_CACHE_MAX_ENTRIES = 10
+_SALES_CACHE_TTL = 600
+
+_DAILY_SALES_PROCESSED_CACHE = {}
+
+_DASHBOARD_DATA_CACHE = {
+    'consolidated_data': None,
+    'consolidated_timestamp': None,
+    'today_start': None,
+    'full_data': None,
+    'full_timestamp': None,
+}
+_DASHBOARD_CACHE_TTL = 1800
+
+
+def cleanup_sales_cache():
+    """清理 sales 處理後快取的過期與超額條目。"""
+    current_time = time.time()
+    expired_keys = [
+        key for key, value in _SALES_PROCESSED_CACHE.items()
+        if value.get('time') and current_time - value['time'] > _SALES_CACHE_TTL
+    ]
+    for key in expired_keys:
+        _SALES_PROCESSED_CACHE.pop(key, None)
+
+    if len(_SALES_PROCESSED_CACHE) > _SALES_CACHE_MAX_ENTRIES:
+        sorted_items = sorted(
+            [(key, value.get('time', 0)) for key, value in _SALES_PROCESSED_CACHE.items()],
+            key=lambda item: item[1],
+        )
+        for key, _ in sorted_items[:-_SALES_CACHE_MAX_ENTRIES]:
+            _SALES_PROCESSED_CACHE.pop(key, None)
+
+
+def set_sales_processed_cache(key, entry, aliases=()):
+    """寫入 sales cache，並可同步寫入別名 key。"""
+    entry.setdefault('time', time.time())
+    _SALES_PROCESSED_CACHE[key] = entry
+    for alias in aliases:
+        _SALES_PROCESSED_CACHE[alias] = entry
+    cleanup_sales_cache()
+
+
+def clear_sales_cache_for_table(table_name):
+    """匯入資料後清除指定表對應的所有 sales cache key。"""
+    _SALES_DF_CACHE.pop(table_name, None)
+    keys_to_delete = [
+        key for key in list(_SALES_PROCESSED_CACHE.keys())
+        if key == table_name or key.startswith(f"{table_name}_")
+    ]
+    for key in keys_to_delete:
+        _SALES_PROCESSED_CACHE.pop(key, None)
+
+
+def clear_sales_cache():
+    """清除所有 sales cache。"""
+    _SALES_DF_CACHE.clear()
+    _SALES_PROCESSED_CACHE.clear()
+    _SALES_OPTIONS_CACHE.clear()
+    _SALES_ANALYSIS_RESULT_CACHE.clear()
+
+
+def clear_daily_sales_cache():
+    """清除當日業績 cache。"""
+    _DAILY_SALES_PROCESSED_CACHE.clear()
+
+
+def clear_dashboard_cache():
+    """清除商品看板 cache。"""
+    _DASHBOARD_DATA_CACHE.clear()
+    _DASHBOARD_DATA_CACHE.update({
+        'consolidated_data': None,
+        'consolidated_timestamp': None,
+        'today_start': None,
+        'full_data': None,
+        'full_timestamp': None,
+    })