web: PWA manifest so the UI installs as a standalone app

api/web.go

@@ -18,6 +18,17 @@ var webOverlayHTML []byte
 //go:embed web/favicon.svg
 var webFaviconSVG []byte
 
+// PWA manifest + icons: lets browsers install the web UI as a standalone
+// app (fullscreen from a home-screen icon on phones/tablets, its own window
+// on desktop). No service worker on purpose — the UI is meaningless without
+// the live server, so offline caching would only mislead.
+//
+//go:embed web/manifest.json
+var webManifestJSON []byte
+
+//go:embed web/icon-192.png web/icon-512.png
+var webIconsFS embed.FS
+
 // webFontsFS holds the self-hosted woff2 fonts (Geist Mono + VT323), served at
 // /fonts/. Bundled into the binary so the UI needs no external font CDN —
 // important since it usually runs offline on the CDJ link-local network.
@@ -45,6 +56,21 @@ func RegisterWebUI(mux *http.ServeMux) {
 		w.Write(webOverlayHTML)
 	})
 
+	mux.HandleFunc("/manifest.json", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/manifest+json")
+		w.Header().Set("Cache-Control", "public, max-age=86400")
+		w.Write(webManifestJSON)
+	})
+	for _, name := range []string{"icon-192.png", "icon-512.png"} {
+		name := name
+		mux.HandleFunc("/"+name, func(w http.ResponseWriter, r *http.Request) {
+			data, _ := webIconsFS.ReadFile("web/" + name)
+			w.Header().Set("Content-Type", "image/png")
+			w.Header().Set("Cache-Control", "public, max-age=86400")
+			w.Write(data)
+		})
+	}
+
 	// App icon (vinyl + the null ∅), used as the browser-tab favicon.
 	mux.HandleFunc("/favicon.svg", func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "image/svg+xml")

api/web/index.html

@@ -5,6 +5,9 @@
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <link rel="icon" type="image/svg+xml" href="/favicon.svg">
+<link rel="manifest" href="/manifest.json">
+<meta name="theme-color" content="#0c0c0f">
+<link rel="apple-touch-icon" href="/icon-192.png">
 <title>Vynull · DJ LINK</title>
 <style>
   /* Self-hosted fonts (no external CDN — works offline on the link-local net). */

api/web/manifest.json

@@ -0,0 +1,13 @@
+{
+  "name": "Vynull",
+  "short_name": "Vynull",
+  "description": "DJ library manager — browse, edit, and serve your library to CDJs over Pro DJ Link.",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#0c0c0f",
+  "theme_color": "#0c0c0f",
+  "icons": [
+    { "src": "/icon-192.png", "sizes": "192x192", "type": "image/png" },
+    { "src": "/icon-512.png", "sizes": "512x512", "type": "image/png" }
+  ]
+}