feat(brand): V-viewfinder favicon set (replaces split-W on photo)

Picked 3a from the favicons-and-logo-v2 iteration: a yellow V cut out of
navy with the harbor photo visible inside — "you are looking at a
photograph framed by the V". The brand's own glyph rather than initials.

What changed:
- favicon-16 / -32 / -64 / icon-192 / icon-512 / apple-touch-icon (180):
  V at 86% of canvas, navy outside, full center-cropped harbor inside,
  yellow stroke-outlined border proportional to size.
- icon-512-maskable: V at 65% of canvas (inside the Android safe zone),
  navy in the outer 35% so circle/squircle launcher masks crop navy
  pixels, not the V.
- favicon.svg: lightweight vector — yellow V outline on navy, no embedded
  photo (kept under 300 bytes so it's fast even before the build cache).
- favicon.ico: multi-resolution 16/32/64 for legacy clients.

Root-level fallbacks (public/apple-touch-icon.png + -precomposed +
favicon.{svg,ico}) updated in lock-step so iOS's Add-to-Home-Screen
probes pick up the new icon without falling back to a cached old one.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/public/favicon.svg

@@ -1,12 +1,6 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64">
-  <defs>
-    <clipPath id="wv-left"><rect x="0" y="0" width="32" height="64"/></clipPath>
-    <clipPath id="wv-right"><rect x="32" y="0" width="32" height="64"/></clipPath>
-  </defs>
-  <rect width="64" height="64" rx="12" fill="#1a3a5c"/>
-  <g font-family="system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif"
-     font-weight="900" font-size="56" text-anchor="middle">
-    <text x="32" y="50" fill="#fafafa" clip-path="url(#wv-left)">W</text>
-    <text x="32" y="50" fill="#f0d000" clip-path="url(#wv-right)">W</text>
-  </g>
+  <rect width="64" height="64" rx="10" fill="#0e2740"/>
+  <path d="M 12 12 L 32 52 L 52 12"
+        stroke="#f0d000" stroke-width="6"
+        stroke-linejoin="round" stroke-linecap="round" fill="none"/>
 </svg>

public/build/favicon.svg

@@ -1,12 +1,6 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64">
-  <defs>
-    <clipPath id="wv-left"><rect x="0" y="0" width="32" height="64"/></clipPath>
-    <clipPath id="wv-right"><rect x="32" y="0" width="32" height="64"/></clipPath>
-  </defs>
-  <rect width="64" height="64" rx="12" fill="#1a3a5c"/>
-  <g font-family="system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif"
-     font-weight="900" font-size="56" text-anchor="middle">
-    <text x="32" y="50" fill="#fafafa" clip-path="url(#wv-left)">W</text>
-    <text x="32" y="50" fill="#f0d000" clip-path="url(#wv-right)">W</text>
-  </g>
+  <rect width="64" height="64" rx="10" fill="#0e2740"/>
+  <path d="M 12 12 L 32 52 L 52 12"
+        stroke="#f0d000" stroke-width="6"
+        stroke-linejoin="round" stroke-linecap="round" fill="none"/>
 </svg>

public/favicon.svg

@@ -1,12 +1,6 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64">
-  <defs>
-    <clipPath id="wv-left"><rect x="0" y="0" width="32" height="64"/></clipPath>
-    <clipPath id="wv-right"><rect x="32" y="0" width="32" height="64"/></clipPath>
-  </defs>
-  <rect width="64" height="64" rx="12" fill="#1a3a5c"/>
-  <g font-family="system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif"
-     font-weight="900" font-size="56" text-anchor="middle">
-    <text x="32" y="50" fill="#fafafa" clip-path="url(#wv-left)">W</text>
-    <text x="32" y="50" fill="#f0d000" clip-path="url(#wv-right)">W</text>
-  </g>
+  <rect width="64" height="64" rx="10" fill="#0e2740"/>
+  <path d="M 12 12 L 32 52 L 52 12"
+        stroke="#f0d000" stroke-width="6"
+        stroke-linejoin="round" stroke-linecap="round" fill="none"/>
 </svg>