fix: dashboard affiche la version dynamique ({{VERSION}})

dashboard.html utilise {{VERSION}}, remplacé par server.v au chargement
via const version de main.v. Plus besoin de maj manuelle du HTML.

dashboard.html

@@ -95,7 +95,7 @@ footer{text-align:center;padding:24px;color:#475569;font-size:.75rem}
 </div>
 </div>
 </div>
-<footer>ntfy-bridge v0.1.0 · Homelab Notification Hub</footer>
+<footer>ntfy-bridge {{VERSION}} · Homelab Notification Hub</footer>
 
 <script>
 function switchTab(name) {

server.v

@@ -85,10 +85,11 @@ pub fn new_app(cfg Config, config_path string, quiet bool) App {
 fn load_dashboard_html(logger Logger) string {
 	// Try dashboard.html from current working directory
 	if os.exists('dashboard.html') {
-		content := os.read_file('dashboard.html') or {
+		mut content := os.read_file('dashboard.html') or {
 			logger.warn('server', 'dashboard', 'failed to read dashboard.html, using fallback')
 			return dashboard_fallback_html()
 		}
+		content = content.replace('{{VERSION}}', 'v${version}')
 		logger.info('server', 'dashboard', 'loaded dashboard.html (${content.len} bytes)')
 		return content
 	}