Claude detection respects payment filter, add project skill

- Backend check-claude-payment accepts optional emails list
- Frontend sends filtered emails when filter is active
- Button label updates to show current filter scope
- Add project skill for development guidance

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mail_api.py

@@ -1222,10 +1222,20 @@ async def _check_claude_payment_for_account(email_addr: str) -> dict:
         }
 
 @app.post("/api/tools/check-claude-payment")
-async def check_claude_payment():
-    """SSE流式扫描所有账户的Claude支付状态"""
+async def check_claude_payment(request: Request):
+    """SSE流式扫描账户的Claude支付状态，支持传入指定邮箱列表"""
+    try:
+        body = await request.json()
+        target_emails = body.get('emails', []) if body else []
+    except Exception:
+        target_emails = []
+
     accounts = await load_accounts_config()
-    emails = list(accounts.keys())
+    if target_emails:
+        # 只检测指定的邮箱（且必须在账户中存在）
+        emails = [e for e in target_emails if e in accounts]
+    else:
+        emails = list(accounts.keys())
 
     async def event_generator():
         total = len(emails)