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).

server/index.js

@@ -793,17 +793,11 @@ function startBackgroundServices() {
   } catch (err) {
     console.warn("cursor usage poll failed to start:", err.message);
   }
-  // Oh My Pi and OpenCode sessions, subagents and token usage, from each CLI's
-  // own session store (omp-usage.js, opencode-usage.js).
-  for (const [name, mod, start] of [
-    ["omp", "./lib/omp-usage", "startOmpUsagePoll"],
-    ["opencode", "./lib/opencode-usage", "startOpencodeUsagePoll"],
-  ]) {
-    try {
-      require(mod)[start](broadcast);
-    } catch (err) {
-      console.warn(`${name} usage poll failed to start:`, err.message);
-    }
+  // Oh My Pi sessions, subagents and token usage, from its own session journals.
+  try {
+    require("./lib/omp-usage").startOmpUsagePoll(broadcast);
+  } catch (err) {
+    console.warn("omp usage poll failed to start:", err.message);
   }
   // Codex/Antigravity hooks the user installed forward through a script whose
   // content names this build; point it here (the command in the tool's