feat(dashboard): optimize cache and AI pick confidence

services/cache_manager.py

@@ -7,7 +7,9 @@ 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 os
 import time
+from pathlib import Path
 
 
 class FingerprintCache:
@@ -59,6 +61,8 @@ _DASHBOARD_DATA_CACHE = {
     'full_timestamp': None,
 }
 _DASHBOARD_CACHE_TTL = 1800
+_BASE_DIR = Path(__file__).resolve().parents[1]
+_DASHBOARD_SHARED_CACHE_FILE = _BASE_DIR / "data" / "dashboard_full_cache.pkl"
 
 
 def cleanup_sales_cache():
@@ -123,3 +127,9 @@ def clear_dashboard_cache():
         'full_data': None,
         'full_timestamp': None,
     })
+    try:
+        os.remove(_DASHBOARD_SHARED_CACHE_FILE)
+    except FileNotFoundError:
+        pass
+    except OSError:
+        pass