Docs: replace default favicon, add git icon, fix Mermaid direction

- Favicon: MSFN antenna dish with signal arcs (NASA blue/red, dark mode)
- Social icon: generic git-branch replacing GitHub-specific icon
- Mermaid signal chain diagram: flowchart TB for vertical readability
- Add astro-icon (with Lucide icons) and astro-opengraph-images packages

docs/astro.config.mjs

@@ -1,16 +1,18 @@
 // @ts-check
 import { defineConfig } from 'astro/config';
 import starlight from '@astrojs/starlight';
+import icon from 'astro-icon';
 import rehypeMermaid from 'rehype-mermaid';
 
+// astro-opengraph-images installed but needs font setup:
+// import astroOpenGraphImages, { presets } from 'astro-opengraph-images';
+
 export default defineConfig({
   integrations: [
+    icon(),
     starlight({
       title: 'gr-apollo',
       description: 'Apollo Unified S-Band decoder for GNU Radio 3.10+',
-      social: [
-        { icon: 'github', label: 'GitHub', href: 'https://github.com/rpm/gr-apollo' },
-      ],
       sidebar: [
         {
           label: 'Getting Started',
@@ -52,6 +54,7 @@ export default defineConfig({
       },
       components: {
         Head: './src/components/Head.astro',
+        SocialIcons: './src/components/SocialIcons.astro',
       },
     }),
   ],

docs/package.json

@@ -11,7 +11,10 @@
   },
   "dependencies": {
     "@astrojs/starlight": "^0.37.6",
+    "@iconify-json/lucide": "^1.2.92",
     "astro": "^5.6.1",
+    "astro-icon": "^1.1.5",
+    "astro-opengraph-images": "^1.14.3",
     "mermaid": "^11.12.3",
     "rehype-mermaid": "^3.0.0",
     "sharp": "^0.34.2"

docs/public/favicon.svg

@@ -1 +1,28 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 128 128"><path fill-rule="evenodd" d="M81 36 64 0 47 36l-1 2-9-10a6 6 0 0 0-9 9l10 10h-2L0 64l36 17h2L28 91a6 6 0 1 0 9 9l9-10 1 2 17 36 17-36v-2l9 10a6 6 0 1 0 9-9l-9-9 2-1 36-17-36-17-2-1 9-9a6 6 0 1 0-9-9l-9 10v-2Zm-17 2-2 5c-4 8-11 15-19 19l-5 2 5 2c8 4 15 11 19 19l2 5 2-5c4-8 11-15 19-19l5-2-5-2c-8-4-15-11-19-19l-2-5Z" clip-rule="evenodd"/><path d="M118 19a6 6 0 0 0-9-9l-3 3a6 6 0 1 0 9 9l3-3Zm-96 4c-2 2-6 2-9 0l-3-3a6 6 0 1 1 9-9l3 3c3 2 3 6 0 9Zm0 82c-2-2-6-2-9 0l-3 3a6 6 0 1 0 9 9l3-3c3-2 3-6 0-9Zm96 4a6 6 0 0 1-9 9l-3-3a6 6 0 1 1 9-9l3 3Z"/><style>path{fill:#000}@media (prefers-color-scheme:dark){path{fill:#fff}}</style></svg>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 128 128">
+  <defs>
+    <style>
+      .s{fill:none;stroke:#0B3D91;stroke-linecap:round;stroke-linejoin:round}
+      .f{fill:#0B3D91}
+      .r{fill:none;stroke:#FC3D21;stroke-linecap:round}
+      @media(prefers-color-scheme:dark){
+        .s{stroke:#7EB8FF}
+        .f{fill:#7EB8FF}
+      }
+    </style>
+  </defs>
+  <!-- Dish reflector -->
+  <path class="s" d="M18 78Q64 108 110 78" stroke-width="10"/>
+  <!-- Struts to feed horn -->
+  <line class="s" x1="34" y1="82" x2="64" y2="42" stroke-width="5"/>
+  <line class="s" x1="94" y1="82" x2="64" y2="42" stroke-width="5"/>
+  <!-- Feed horn -->
+  <circle class="f" cx="64" cy="40" r="6"/>
+  <!-- Pedestal -->
+  <line class="s" x1="64" y1="88" x2="64" y2="116" stroke-width="8"/>
+  <!-- Base plate -->
+  <line class="s" x1="44" y1="116" x2="84" y2="116" stroke-width="8"/>
+  <!-- Signal arcs -->
+  <path class="r" d="M56 30Q64 22 72 30" stroke-width="4"/>
+  <path class="r" d="M48 22Q64 10 80 22" stroke-width="4" opacity=".65"/>
+  <path class="r" d="M40 14Q64-2 88 14" stroke-width="4" opacity=".35"/>
+</svg>

docs/src/components/SocialIcons.astro

@@ -0,0 +1,33 @@
+---
+// Generic Git icon replacing Starlight's GitHub-specific social icon
+---
+
+<a href="https://github.com/rpm/gr-apollo" rel="me" class="sl-flex git-link" aria-label="Source code">
+  <svg
+    aria-hidden="true"
+    width="1em"
+    height="1em"
+    viewBox="0 0 24 24"
+    fill="none"
+    stroke="currentColor"
+    stroke-width="2"
+    stroke-linecap="round"
+    stroke-linejoin="round"
+  >
+    <line x1="6" y1="3" x2="6" y2="15" />
+    <circle cx="18" cy="6" r="3" />
+    <circle cx="6" cy="18" r="3" />
+    <path d="M18 9a9 9 0 0 1-9 9" />
+  </svg>
+</a>
+
+<style>
+  .git-link {
+    color: var(--sl-color-text-accent);
+    text-decoration: none;
+    padding: 0.5em;
+  }
+  .git-link:hover {
+    opacity: 0.66;
+  }
+</style>

docs/src/content/docs/getting-started/introduction.mdx

@@ -31,7 +31,7 @@ gr-apollo provides a set of GNU Radio blocks and pure-Python engines that implem
 The downlink receiver processes a phase-modulated carrier through five stages. Each stage has a standalone GNU Radio block, or you can use `usb_downlink_receiver` which chains them together.
 
 ```mermaid
-flowchart LR
+flowchart TB
     A["Complex<br/>Baseband<br/>5.12 MHz"] --> B["PM Demod<br/><em>Carrier PLL +<br/>phase extraction</em>"]
     B --> C["Subcarrier<br/>Extract<br/><em>BPF + translate<br/>1.024 MHz → DC</em>"]
     C --> D["BPSK Demod<br/><em>Costas loop +<br/>symbol sync</em>"]