§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test could previously reach the real api.moonshot.cn), and the outdated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/notes.rs

@@ -69,7 +69,7 @@ pub(super) fn dispatch_send_feedback(app: &mut AppView, text: String) -> Vec<Eff
     };
 
     agent.scrollback.push_block(RenderBlock::system(
-        "Thanks for the feedback! The Grok Build team is on it.".to_string(),
+        "Thanks for the feedback! The Kigi team is on it.".to_string(),
     ));
 
     vec![Effect::SendFeedback {
@@ -79,7 +79,7 @@ pub(super) fn dispatch_send_feedback(app: &mut AppView, text: String) -> Vec<Eff
     }]
 }
 
-/// Send a raw remember note for LLM-powered rewriting via `x.ai/memory/rewrite`.
+/// Send a raw remember note for LLM-powered rewriting via `kigi/memory/rewrite`.
 /// Clears remember mode and prompts the LLM to reformat the note with session
 /// context. Falls back to direct `SaveMemoryNote` when no session is available.
 pub(super) fn dispatch_send_remember_note(app: &mut AppView, text: String) -> Vec<Effect> {
@@ -327,7 +327,7 @@ pub(crate) fn scrollback_has_user_messages(
 }
 
 /// Request a session recap. Bypasses the prompt queue — works even while the
-/// agent is mid-turn. Fires the `x.ai/recap` ext method; the recap arrives
+/// agent is mid-turn. Fires the `kigi/recap` ext method; the recap arrives
 /// asynchronously as a `SessionRecap` notification (rendered in scrollback).
 ///
 /// `auto` is `false` for an explicit `/recap` and `true` for the automatic
@@ -343,7 +343,7 @@ pub(super) fn dispatch_send_recap(app: &mut AppView, auto: bool) -> Vec<Effect>
     };
 
     // Shell is authoritative (remote settings / config / env). Skip client requests
-    // entirely when the feature is off so we never hit `x.ai/recap`.
+    // entirely when the feature is off so we never hit `kigi/recap`.
     if !app.session_recap_available {
         if !auto {
             agent.show_toast("Session recap is not enabled");
@@ -420,7 +420,7 @@ pub(super) fn handle_memory_note_saved(
                     .scrollback
                     .push_block(crate::scrollback::block::RenderBlock::system(format!(
                         "Memory saved to {}",
-                        crate::util::display_user_grok_path("memory/MEMORY.md")
+                        crate::util::display_user_kigi_path("memory/MEMORY.md")
                     )));
             }
             Err(error) => {