fix: the PWA install icon uses the current logo

The icon PNGs still carried the old two-leaf motif; only favicon.svg was
updated in the redesign, and Chrome takes the PNGs for the install icon.
Re-rendered both from the current logo, added a padded maskable variant
so Android's mask no longer clips the leaves, bumped the service-worker
cache so existing installs drop the stale icons, and removed the
unreferenced old favicon and wordmark files.

public/favicon-j1.svg

@@ -1,5 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
-  <line x1="6" y1="31" x2="26" y2="31" stroke="#202b36" stroke-width="1.5" opacity="0.6"/>
-  <path transform="translate(11,31)" d="M0,0 C-3.895,-9.912 -2.832,-19.824 0,-25.488 C2.832,-19.824 3.895,-9.912 0,0 Z" fill="#4c6c8a"/>
-  <path transform="translate(21,31)" d="M0,0 C-4.583,-11.667 -3.333,-23.333 0,-29.167 C3.333,-23.333 4.583,-11.667 0,0 Z" fill="#d1734f"/>
-</svg>

public/favicon-old.svg

@@ -1,4 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
-  <rect width="24" height="30" x="4" y="1" rx="2" fill="#fff" stroke="#334155" stroke-width="1.5"/>
-  <path d="M8 8h16M8 13h16M8 18h12M8 23h14" stroke="#3b82f6" stroke-width="1.5" stroke-linecap="round"/>
-</svg>

public/manifest.webmanifest

@@ -14,7 +14,7 @@
     { "src": "favicon.svg", "sizes": "any", "type": "image/svg+xml" },
     { "src": "icon-192.png", "sizes": "192x192", "type": "image/png" },
     { "src": "icon-512.png", "sizes": "512x512", "type": "image/png" },
-    { "src": "icon-512.png", "sizes": "512x512", "type": "image/png", "purpose": "maskable" }
+    { "src": "icon-maskable-512.png", "sizes": "512x512", "type": "image/png", "purpose": "maskable" }
   ],
   "file_handlers": [
     {

public/sw.js

@@ -2,7 +2,7 @@
 // localStorage/IndexedDB — so a cached shell is the whole working editor: dictionaries,
 // fonts and the WASM speller included, each kept the first time it is asked for.
 
-const CACHE = 'edentext-v1';
+const CACHE = 'edentext-v2';
 // The entry document under one key, whichever path asked for it. Relative, so it
 // resolves against this script's own directory — the app root under any base path.
 const SHELL = './';