chore(logo): commit the rendered PNGs, and correct what the mark is

docs/logo/README.md

@@ -1,13 +1,38 @@
 # Agentmetry logo assets
 
-Radar-ring observability mark + clean sans wordmark for the Agentmetry brand.
+Chevron **A** monogram with an orange record pulse, plus a clean sans wordmark.
+
+The dot is doing two jobs: it is the letter's counter and it is the record light
+of a flight recorder. One idea, so the mark survives at 16px.
+
+## Source (SVG)
 
 | File | Use |
 |------|-----|
 | `agentmetry-logo-black.svg` | README (light mode), light backgrounds |
 | `agentmetry-logo-white.svg` | README (dark mode), dark backgrounds |
 | `agentmetry-icon.svg` | `currentColor` icon for theming |
 
-**Mark:** stylized **A** monogram with audit-log lines, radar sweep arc, and orange record pulse at the apex.
+## Rendered (PNG)
+
+GitHub will not accept SVG for a social preview or an avatar, so these are
+raster copies at the sizes those surfaces want.
+
+| File | Size | Use |
+|------|------|-----|
+| `social-preview.png` | 1280x640 | Repo Settings, General, Social preview. The card that renders when the repo URL is shared |
+| `avatar-dark.png` | 512x512 | Account or organization avatar, dark ground. Reads better at 20px |
+| `avatar-orange.png` | 512x512 | Same, orange ground |
+
+Generated from the SVG rather than drawn, so the mark cannot drift between them:
+
+```bash
+cd apps/dashboard
+node -e "require('sharp')('../../docs/logo/agentmetry-icon.svg',{density:288}).resize(512,512).png().toFile('out.png')"
+```
+
+Text in the social preview uses a system font stack (Segoe UI, Arial,
+Helvetica), not Inter, because the renderer cannot be relied on to have a
+webfont installed and a missing face silently drops the wordmark.
 
 Dashboard copies live in `apps/dashboard/public/`.