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/src/lib/types.ts

@@ -732,10 +732,9 @@ export interface Session {
   /** The AI coding CLI that produced the session: `"claude"` (the default —
    * Claude Code's hooks and imported transcripts), `"codex"` (Codex's rollout
    * journals and hooks), `"antigravity"` (agy's conversation files and
-   * hooks), `"cursor"` (Cursor's agent transcripts, no tokens), `"omp"`,
-   * `"opencode"` (their own session stores, with tokens and subagents) or
-   * `"grok"` (Grok running the Claude hooks, no tokens). Maps to
-   * `sessions.tool`. */
+   * hooks), `"cursor"` (Cursor's agent transcripts, no tokens) or `"omp"`
+   * (its own session journals, with tokens and subagents). Rows an older build
+   * wrote may still say `"opencode"` or `"grok"`. Maps to `sessions.tool`. */
   tool?: string;
   /** The workspace (lane id) that owns the session — the one whose pane held
    * it; null for a session no workspace started.
@@ -1217,7 +1216,7 @@ export interface CostResult {
 
 /** GET /api/pricing/quota: plan quota spent per native tool (server/lib/quota.js). */
 export interface ToolQuota {
-  id: "claude" | "codex" | "antigravity" | "cursor" | "grok" | "kimi" | "opencode";
+  id: "claude" | "codex" | "antigravity" | "cursor" | "kimi";
   /** One per plan window: `5h`, `wk`, `mo`, …; `usedPercent` is 0–100.
    *  `group` names the model pool a window belongs to (Antigravity's). */
   windows: Array<{