feat: default to all modes, switch mode filter from whitelist to excludedModes blacklist

- NotifyConfig.modes (whitelist) → excludedModes (blacklist, default [] = push everywhere)
- valid modes are tui/json/rpc/print (pi ExtensionMode); invalid entries ignored with warning
- legacy "modes" key is ignored with a deprecation warning
- /ntfy status shows 模式: 全部（排除: json）
- migrate local config: modes array → excludedModes: []

config.example.json

@@ -1,8 +1,8 @@
 {
-  "_说明": "pi-ntfy 只支持 NTFY。复制为 config.json 后按需修改。",
+  "_说明": "pi-ntfy 只支持 NTFY。默认所有工作模式（tui/json/rpc/print）都会推送；excludedModes 仅列出不需要推送的模式，例如 [\"json\"] 可让 pi --mode json -p 的子代理保持安静。复制为 config.json 后按需修改。",
   "_占位符": "{{status}} {{reason}} {{text}} {{title}} {{event}} {{cwd}} {{project}} {{duration}} {{session}} {{sessionId}} {{model}} {{mode}} {{thinking}} {{task}} {{summary}} {{tools}} {{host}} {{time}} {{date}}",
   "enabled": true,
-  "modes": ["tui"],
+  "excludedModes": [],
   "timeoutMs": 5000,
   "shutdownTimeoutMs": 2000,
   "dedupeMs": 3000,