feat(marca): atualiza logo, ícones, manifest e Open Graph para a identidade atual (#3)

- Logo em duas cores (teal + cobre), inline no cabeçalho e rodapé para
  seguir o tema do site; SVGs estáticos com prefers-color-scheme.
- scripts/generate-favicons.mjs passa a gerar favicons, ícones de app
  (maskable), site.webmanifest e a imagem Open Graph 1200x630.
- Manifest com fundo/tema obsidiana e lang pt-BR.


Claude-Session: https://claude.ai/code/session_016W1xmizFcmXLrmabSvfSuc

Co-authored-by: Claude Sonnet 5.5 <noreply@anthropic.com>

public/marca/espdocs-lockup.svg

@@ -1,19 +1,18 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 260 64" role="img" aria-label="ESPDocs">
   <title>ESPDocs</title>
-  <defs>
-    <linearGradient id="gl" x1="6" y1="58" x2="250" y2="6" gradientUnits="userSpaceOnUse">
-      <stop offset="0" stop-color="#24645f"/>
-      <stop offset="0.55" stop-color="#8a3410"/>
-      <stop offset="1" stop-color="#c4744f"/>
-    </linearGradient>
-  </defs>
-  <g stroke="url(#gl)" stroke-width="3.4" stroke-linecap="round">
+  <style>
+    .p{stroke:#0a5852}.l{stroke:#823626}.t{fill:#0b0d10}
+    @media (prefers-color-scheme: dark){.p{stroke:#2dd4bf}.l{stroke:#ffb39b}.t{fill:#f4f6f8}}
+  </style>
+  <!-- Pinos entrando pela esquerda: o sinal que chega do silício. -->
+  <g class="p" fill="none" stroke-width="3.4" stroke-linecap="round">
     <path d="M2 21h7"/><path d="M2 32h7"/><path d="M2 43h7"/>
   </g>
-  <rect x="9.25" y="9.25" width="45.5" height="45.5" rx="13" fill="none" stroke="url(#gl)" stroke-width="4.5"/>
-  <g stroke="url(#gl)" stroke-width="4.5" stroke-linecap="round">
+  <!-- Corpo do encapsulamento. -->
+  <rect class="p" x="9.25" y="9.25" width="45.5" height="45.5" rx="13" fill="none" stroke-width="4.5"/>
+  <!-- Os mesmos três níveis viram linhas de texto: a documentação. -->
+  <g class="l" fill="none" stroke-width="4.5" stroke-linecap="round">
     <path d="M19 21h26"/><path d="M19 32h21"/><path d="M19 43h15"/>
   </g>
-  <text x="72" y="43" font-family="Outfit, Inter, system-ui, sans-serif" font-size="34"
-        font-weight="800" letter-spacing="-0.5" fill="url(#gl)">ESPDocs</text>
+  <text class="t" x="72" y="43" font-family="'Space Grotesk', Inter, system-ui, sans-serif" font-size="34" font-weight="600" letter-spacing="-1.5">ESPDocs</text>
 </svg>