§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test could previously reach the real api.moonshot.cn), and the outdated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-tui/src/app/dispatch/status.rs

@@ -8,7 +8,7 @@ use crate::app::app_view::{ActiveView, AppView};
 use crate::notifications::{NotificationEvent, NotificationEventKind};
 use crate::scrollback::block::RenderBlock;
 
-/// Show session info: fetch via x.ai/session/info and display in scrollback.
+/// Show session info: fetch via kigi/session/info and display in scrollback.
 ///
 /// Produces Effect::ShowSessionInfo which spawns an async ACP ext request.
 /// On completion, TaskResult::SessionInfoComplete shows the formatted info.
@@ -49,7 +49,7 @@ pub(super) fn scrub_error_for_toast(error: &str) -> String {
     }
 }
 
-/// Show context info: fetch via x.ai/session/info and display rich breakdown.
+/// Show context info: fetch via kigi/session/info and display rich breakdown.
 ///
 /// Produces Effect::ShowContextInfo which spawns an async ACP ext request.
 /// On completion, TaskResult::ContextInfoComplete shows the formatted info.
@@ -72,7 +72,7 @@ pub(super) fn dispatch_show_context_info(app: &mut AppView) -> Vec<Effect> {
 
 /// `/usage` — fetch Kimi usage/quota rows and display them inline.
 ///
-/// Produces [`Effect::FetchUsage`], which asks the shell's `x.ai/billing`
+/// Produces [`Effect::FetchUsage`], which asks the shell's `kigi/billing`
 /// extension (`GET {base}/usages`); [`handle_usage_fetched`] renders the
 /// rows as a system block in scrollback.
 pub(super) fn dispatch_show_usage(app: &mut AppView) -> Vec<Effect> {
@@ -225,7 +225,7 @@ pub(super) fn notify_session_ready(
 ) {
     notification_service.notify(NotificationEvent {
         kind: NotificationEventKind::SessionReady,
-        title: "Grok".into(),
+        title: "Kigi".into(),
         body: NotificationEventKind::SessionReady.as_str().into(),
         session_id: agent.session.session_id.as_ref().map(|s| s.0.to_string()),
     });