chore(branding): multi-modal press kit, hero OG + dashboard.gif (#323)

- Recolor banner/wordmark SVGs to the Otter Orange palette with brand fonts
- Rebuild social-preview.png as a hero-style OG card (trust badges, headline, five modality cards with section counts), synced to apps/landing + apps/web og-image.png
- Replace static dashboard PNGs with dashboard.gif: a guided tab tour of all 157 tools across the five modalities
- Update branding/README.md (Otter Palette, brand fonts, asset list); add scripts/branding generator + sync helpers

branding/wordmark.svg

@@ -1,5 +1,5 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 400 80" fill="none">
-  <text x="0" y="58" font-family="Nunito, Inter, system-ui, sans-serif" font-size="56" font-weight="800" fill="#0f172a">
-    <tspan>Snap</tspan><tspan fill="#3b82f6">Otter</tspan>
+  <text x="0" y="58" font-family="'Bricolage Grotesque', 'Nunito', system-ui, sans-serif" font-size="56" font-weight="800" fill="#1A1814">
+    <tspan>Snap</tspan><tspan fill="#E07832">Otter</tspan>
   </text>
 </svg>