feat: placeholder app icons (clock-with-target motif)

Generate the manifest/PWA + native-wrapper icons that were referenced but
missing (icon-192/512 were 404). A reproducible pure-Node generator
(tools/gen-icons.mjs, npm run gen:icons) draws a clock ring with amber
hands + a green target dot in the app palette — no image deps, hand-rolled
PNG encoder with analytic anti-aliasing.

- public/icons/icon-192, -512, -180 (apple-touch); linked in index.html.
- resources/icon.png (1024) + splash.png (2732) for @capacitor/assets.
- tests/tools/icons.test.js ties every manifest icon to a real PNG of the
  declared size. 213 tests pass; icons now serve 200.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

index.html

@@ -6,6 +6,8 @@
     <title>The Director</title>
     <link rel="stylesheet" href="/src/styles.css" />
     <link rel="manifest" href="/manifest.webmanifest" />
+    <link rel="apple-touch-icon" href="/icons/icon-180.png" />
+    <link rel="icon" type="image/png" sizes="512x512" href="/icons/icon-512.png" />
     <meta name="theme-color" content="#0b0e13" />
     <!-- iOS home-screen / native-wrapper hints -->
     <meta name="apple-mobile-web-app-capable" content="yes" />