feat(ai-tools): drop OpenCode and Grok Build

- opencode.json / grok.json leave the built-in catalog; opencode-usage.js,
  its poller, transcript branch and table creation go with it (existing
  tables and session rows stay as history).
- A Grok payload reaching the Claude hook route (Grok runs the Claude hooks
  itself) is dropped instead of recorded as tool = 'grok'.
- quota.js no longer reads Grok or OpenCode Go logins.
- Redone on v2.8.22 from c6b2892 (feat/grok-usage, never merged).

client/public/og-image.svg

@@ -49,7 +49,7 @@
     <g transform="translate(20,22)"><rect width="48" height="48" rx="12" fill="#4cc3f5" fill-opacity="0.12"/><rect x="11" y="11" width="11" height="11" rx="3" fill="#4cc3f5"/><rect x="26" y="11" width="11" height="11" rx="3" fill="none" stroke="#4cc3f5" stroke-width="2.5"/><rect x="11" y="26" width="11" height="11" rx="3" fill="none" stroke="#4cc3f5" stroke-width="2.5"/><rect x="26" y="26" width="11" height="11" rx="3" fill="#4cc3f5"/></g>
     <text x="84" y="44" font-family="'Inter', 'Segoe UI', 'Helvetica Neue', Arial, sans-serif" font-size="21" font-weight="700" fill="#f1f5ff">Every AI coding agent</text>
     <text x="84" y="72" font-family="'Inter', 'Segoe UI', 'Helvetica Neue', Arial, sans-serif" font-size="16" fill="#9aa6c4">Claude Code, Codex, Antigravity,</text>
-    <text x="84" y="94" font-family="'Inter', 'Segoe UI', 'Helvetica Neue', Arial, sans-serif" font-size="16" fill="#9aa6c4">Cursor, Kimi, Grok and more</text>
+    <text x="84" y="94" font-family="'Inter', 'Segoe UI', 'Helvetica Neue', Arial, sans-serif" font-size="16" fill="#9aa6c4">Cursor, omp and more</text>
   </g>
   <g transform="translate(792,300)">
     <rect width="344" height="116" rx="16" fill="#ffffff" fill-opacity="0.045" stroke="#ffffff" stroke-opacity="0.10"/>