fix: serve PWA manifest dynamically to respect runtime APP_NAME env var

Delete static public/manifest.json (hardcoded "Bulwark Webmail") and mark
app/manifest.ts as force-dynamic so Next.js evaluates APP_NAME at request
time instead of build time, fixing the native browser install prompt.

Closes #207

app/manifest.ts

@@ -1,5 +1,7 @@
 import type { MetadataRoute } from "next";
 
+export const dynamic = "force-dynamic";
+
 export default function manifest(): MetadataRoute.Manifest {
   const appName =
     process.env.APP_NAME ||

public/manifest.json

@@ -1,68 +0,0 @@
-{
-  "name": "Bulwark Webmail",
-  "short_name": "Bulwark",
-  "description": "A modern webmail client built for Stalwart Mail Server",
-  "start_url": "/",
-  "scope": "/",
-  "display": "standalone",
-  "orientation": "portrait-primary",
-  "theme_color": "#ffffff",
-  "background_color": "#ffffff",
-  "icons": [
-    {
-      "src": "/icon-192x192.png",
-      "sizes": "192x192",
-      "type": "image/png",
-      "purpose": "any"
-    },
-    {
-      "src": "/icon-512x512.png",
-      "sizes": "512x512",
-      "type": "image/png",
-      "purpose": "any"
-    },
-    {
-      "src": "/icon-maskable-light-192x192.png",
-      "sizes": "192x192",
-      "type": "image/png",
-      "purpose": "maskable",
-      "media": "(prefers-color-scheme: light)"
-    },
-    {
-      "src": "/icon-maskable-light-512x512.png",
-      "sizes": "512x512",
-      "type": "image/png",
-      "purpose": "maskable",
-      "media": "(prefers-color-scheme: light)"
-    },
-    {
-      "src": "/icon-maskable-dark-192x192.png",
-      "sizes": "192x192",
-      "type": "image/png",
-      "purpose": "maskable",
-      "media": "(prefers-color-scheme: dark)"
-    },
-    {
-      "src": "/icon-maskable-dark-512x512.png",
-      "sizes": "512x512",
-      "type": "image/png",
-      "purpose": "maskable",
-      "media": "(prefers-color-scheme: dark)"
-    }
-  ],
-  "categories": ["productivity"],
-  "screenshots": [
-    {
-      "src": "/screenshot-540x720.png",
-      "sizes": "540x720",
-      "type": "image/png",
-      "form_factor": "narrow"
-    },
-    {
-      "src": "/screenshot-1280x720.png",
-      "sizes": "1280x720",
-      "type": "image/png",
-      "form_factor": "wide"
-    }
-  ]
-}