feat(controller): hot-reload the notification pipes

Email, ntfy and webhook kept their settings in a plain struct field copied at
construction, so editing controllerMethod in config.json wrote the file and
replaced the in-memory configuration while the running channels stayed on their
boot values.

Add Reload to the Controller interface and implement it for the three
notification pipes; Manager.ReloadAll fans an update out to every registered
controller and is wired into the reload hook from main.

Reload runs on the goroutine serving the settings update while the send methods
run on the status-change and incoming-webhook goroutines, so storing the new
settings in a plain field would be a data race. Each pipe publishes its settings
— and the HTTP client derived from them — through atomic pointers, and every
send takes one snapshot so a reload landing mid-send cannot split it across two
configurations.

Only a change to networkUseProxy rebuilds the client; everything else is read
from the settings at send time, so a reload that changes nothing relevant leaves
the client alone. Email needed one more fix: gomail exposes its dial hook as a
package-level variable with no unset, and the constructor only installed the
proxy dialer when the flag was set, so turning networkUseProxy off left SMTP
tunnelled through a proxy. applyEmailProxy now restores net.DialTimeout, which
is gomail's own default.

QQ (Napcat) and Telegram implement Reload because the interface requires it, but
neither can apply a change in place: the NapCat client is stopped through a
sync.Once and the Telegram polling context is created with the controller, so
both need to be rebuilt and swapped into the manager. Rather than no-op silently
and let an edit look applied, they log a warning while their settings diverge.
That rebuild is the next step.

internal/controller/pipes/qq_napcat/qq.go

@@ -86,6 +86,23 @@ func (q *QQController) IsEnabled() bool {
 	return q.cfg.Enabled
 }
 
+// Reload is not implemented yet for this channel.
+//
+// Everything this controller uses — the NapCat address, port and token — is
+// captured in the client it connected with, and that client's WebSocket
+// listener is stopped through a sync.Once and cannot be re-pointed. Applying a
+// change therefore means stopping the client and building a replacement
+// controller, which lands together with the Telegram one. Until then the
+// divergence is reported rather than ignored, so an edit that needs a restart
+// does not look like it took effect.
+func (q *QQController) Reload() {
+	global := config.Current()
+	if global == nil || q.cfg == global.ControllerMethod.QQ {
+		return
+	}
+	postLog.Warning("QQ (Napcat) settings changed but hot reload is not implemented for this channel yet; restart to apply them")
+}
+
 // IsMarkdown returns whether the channel renders Markdown, per its markdown
 // setting in config.json.
 func (q *QQController) IsMarkdown() bool {