§9 acceptance: grep-zero sweep — every internal x.ai/grok identifier renamed

The PRD's first acceptance gate now holds: grep -RinE '\bx\.ai\b|grok'
crates/ --include='*.rs' → 0 matches (exempt: NOTICE and third-party
license archives, README provenance, and the required 'Based on Grok
Build Open Source' attribution, now sourced from version_attribution.txt).

Wire-visible renames (both sides in this repo, changed in lockstep):
- Auth method id 'grok.com' → 'kimi-code' (AuthMethodKind::KimiCode).
- Every x.ai/* and _x.ai/* ACP ext method and meta key → kigi/* /
  _kigi/* (~200 names; grokShell → kigiShell). Session-file replay keeps
  a read-side alias for the legacy '_x.ai/session/update' method so
  existing updates.jsonl histories load; writes emit only the new name
  (both directions test-pinned).
- Agent types grok-build* → kigi* with a documented legacy-prefix alias
  at resolution time so persisted sessions keep resolving.
- ToolNamespace/BuiltinAgentName GrokBuild* → Kigi* (wire snake_case
  kigi/kigi_concise/kigi_hashline; schema regenerated); grok_build
  implementation dirs renamed to kigi*.
- x-grok-* headers → x-kigi-*, __GROK_* sentinels → __KIGI_*, themes
  grokday/groknight → kigiday/kiginight (old persisted values fall back
  to the default theme), web_fetch allowlist xAI hosts → kimi.com +
  moonshot platforms, changelog CDN → this repo, grok-build changelog
  archives deleted.
- BYOK default endpoint removed: [endpoints] api_base_url is now truly
  optional with NO default — consumers fail fast with the flag name when
  unset (no silent x.ai egress). Mock harnesses inject it explicitly.
- System-prompt identity fixed: 'released by xAI' → 'an unofficial
  community CLI for Kimi' (template + regenerated encrypted form).

Also repaired pre-existing grok-era test debt found by the sweep: the
stale trace_classify default-model pin, the grok-pager UA label test,
pty-harness stale-binary reuse and non-hermetic moonshot routing (a PTY
test could previously reach the real api.moonshot.cn), and the outdated
oauth fixture scope key.

Gates: §9 grep 0; fmt clean; workspace check/clippy 0/0 (-D warnings);
FULL cargo test --workspace: 234 suites, 21,961 passed, 0 failed;
deny advisories ok.

crates/codegen/kigi-shell/tests/test_subagent_orphan_reconcile.rs

@@ -6,7 +6,7 @@
 //! session's `subagents/` dir and flips any stale `running` meta (not tracked by
 //! the live coordinator) to `cancelled` (mechanism A, the meta pass).
 //!
-//! This test spawns a real `grok agent stdio` process, seeds an orphaned
+//! This test spawns a real `kigi agent stdio` process, seeds an orphaned
 //! `running` meta on disk, resumes the session, and asserts the meta was
 //! reconciled to `cancelled`.
 //!
@@ -57,7 +57,7 @@ async fn resume_reconciles_orphaned_running_subagent() {
         let workdir = git_workdir();
 
         // Phase 1: create a real session, then take its home so we can seed it.
-        let mut writer = GrokStdioClient::spawn(&server, workdir.path()).await;
+        let mut writer = KigiStdioClient::spawn(&server, workdir.path()).await;
         writer.initialize_with_timeout().await;
         let session_id = writer.create_session_with_timeout(workdir.path()).await;
         let shared_home = writer.take_home();
@@ -66,7 +66,7 @@ async fn resume_reconciles_orphaned_running_subagent() {
         // Simulate a crash: inject a subagent meta left `running` on disk (no
         // terminal write, no SubagentFinished) — exactly what a dead process
         // leaves behind.
-        // GrokStdioClient sets HOME=<temp>; the binary uses <HOME>/.kigi as KIGI_SHARE_DIR.
+        // KigiStdioClient sets HOME=<temp>; the binary uses <HOME>/.kigi as KIGI_SHARE_DIR.
         let kigi_home = shared_home.path().join(".kigi");
         let session_dir = locate_session_dir(&kigi_home, session_id.0.as_ref());
         let sub_id = "sa-orphan";
@@ -89,7 +89,7 @@ async fn resume_reconciles_orphaned_running_subagent() {
         .unwrap();
 
         // Phase 2: resume in a fresh process. `load_session` runs the reconcile.
-        let reader = GrokStdioClient::spawn_with_home(&server, workdir.path(), shared_home).await;
+        let reader = KigiStdioClient::spawn_with_home(&server, workdir.path(), shared_home).await;
         reader.initialize_with_timeout().await;
         let _ = reader
             .load_session_with_timeout(&session_id, workdir.path())