Add ntfy Basic auth, sign-out button, config-only credentials

- ntfy client supports HTTP Basic auth (username/password) for servers with
  access control; [ntfy] config gains username/password. Scheduler + Test Ntfy
  use it instead of the old settings-only bearer token.
- Settings page no longer has credential inputs (Apify/eBay/ntfy/Resend); they
  are managed in config.toml. Read-only status + Test buttons remain.
- Sidebar gains a Sign out button; in forward-auth mode it routes through the
  Authentik outpost sign_out so the IdP session is cleared.

templates/settings.templ

@@ -67,21 +67,21 @@ templ settingsBody(d SettingsData) {
 
 		<section class="v-card p-6">
 			<h2 class="v-section-title mb-4">Apify, eBay and Ntfy</h2>
+			<div class="v-muted text-sm mb-4">
+				API credentials (Apify, eBay, ntfy, Resend) are managed in config.toml on the server, not here. Use the Test buttons to verify them.
+			</div>
 			<form method="post" action="/settings" class="space-y-4">
 				@CSRFInput(d.CSRFToken)
 				<div>
 					<label class="v-label">Apify API Key</label>
-					<input class="v-input font-mono" type="password" name="apify_api_key" autocomplete="off" placeholder="leave blank to keep current value"/>
 					@credStatus(d, "apify_api_key")
 				</div>
 				<div class="border-t border-white/10 pt-4">
 					<label class="v-label">eBay App ID (Client ID)</label>
-					<input class="v-input font-mono" type="password" name="ebay_client_id" autocomplete="off" placeholder="used for eBay marketplaces instead of Apify"/>
 					@credStatus(d, "ebay_client_id")
 				</div>
 				<div>
 					<label class="v-label">eBay Cert ID (Client Secret)</label>
-					<input class="v-input font-mono" type="password" name="ebay_client_secret" autocomplete="off" placeholder="leave blank to keep current value"/>
 					@credStatus(d, "ebay_client_secret")
 				</div>
 				<div>
@@ -108,9 +108,8 @@ templ settingsBody(d SettingsData) {
 					<input class="v-input" name="ntfy_default_topic" value={ d.Values["ntfy_default_topic"] }/>
 				</div>
 				<div>
-					<label class="v-label">Ntfy Token</label>
-					<input class="v-input font-mono" type="password" name="ntfy_token" autocomplete="off" placeholder="tk_... (leave blank to keep current value)"/>
-					@credStatus(d, "ntfy_token")
+					<label class="v-label">Ntfy Auth (user / password)</label>
+					@credStatus(d, "ntfy_auth")
 				</div>
 				<div>
 					<label class="v-label">Global Poll Interval (minutes)</label>
@@ -122,7 +121,6 @@ templ settingsBody(d SettingsData) {
 				</div>
 				<div class="border-t border-white/10 pt-4">
 					<label class="v-label">Resend API Key</label>
-					<input class="v-input font-mono" type="password" name="resend_api_key" autocomplete="off" placeholder="re_... (leave blank to keep current value)"/>
 					@credStatus(d, "resend_api_key")
 				</div>
 				<div>