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/__tests__/pty-run.test.js

@@ -733,7 +733,7 @@ describe("pty-run", () => {
     let savedPath;
     before(() => {
       fs.mkdirSync(BIN, { recursive: true });
-      for (const name of ["agy", "grok", "goose", "command-code", "omp"]) {
+      for (const name of ["agy", "septool", "goose", "command-code", "omp"]) {
         fs.writeFileSync(path.join(BIN, name), "#!/bin/sh\n");
         fs.chmodSync(path.join(BIN, name), 0o755);
       }
@@ -854,7 +854,7 @@ describe("pty-run", () => {
         );
       assert.deepEqual(argvFor("antigravity"), [at("agy"), "-i", " -x y"]);
       // Behind a `--` separator the prompt is already a positional, kept as typed.
-      assert.deepEqual(argvFor("grok"), [at("grok"), "--", "-x y"]);
+      assert.deepEqual(argvFor("septool"), [at("septool"), "--", "-x y"]);
       assert.deepEqual(argvFor("command-code"), [at("command-code"), "--trust", " -x y"]);
       assert.deepEqual(argvFor("antigravity", { bypass: false }), [at("agy"), "-i", " -x y"]);
     });