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test could previously reach the real api.moonshot.cn), and the outdated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

@@ -518,7 +518,7 @@ async fn doomed_then_reasoning_only_empty_coexist() {
 
 /// `[doom_loop_recovery] enabled = true` in `config.toml` reaches the wire
 /// through the real binary: the session TURN request (marked by
-/// `x-grok-turn-idx`) carries the opt-in header. Aux side-queries the binary
+/// `x-kigi-turn-idx`) carries the opt-in header. Aux side-queries the binary
 /// also fires at `/v1/responses` (e.g. session-title generation) must NOT
 /// carry it — they collect without the actor's retry loop, so an armed
 /// abort there could only fail them, never resample. The recovery behavior
@@ -546,7 +546,7 @@ async fn headless_config_enables_doom_loop_check_header() {
     )
     .expect("write config.toml");
 
-    let mut cmd = tokio::process::Command::new(kigi_test_support::grok_binary());
+    let mut cmd = tokio::process::Command::new(kigi_test_support::kigi_binary());
     cmd.args(["-p", "say hi", "--yolo", "--output-format", "json"])
         .arg("--cwd")
         .arg(workdir.path())
@@ -568,11 +568,11 @@ async fn headless_config_enables_doom_loop_check_header() {
         .iter()
         .filter(|e| e.method == "POST" && e.path.contains("/responses"))
         .collect();
-    // The session turn carries `x-grok-turn-idx`; aux side-queries (session
+    // The session turn carries `x-kigi-turn-idx`; aux side-queries (session
     // title, etc.) do not.
     let (turns, aux): (Vec<_>, Vec<_>) = responses_posts
         .into_iter()
-        .partition(|e| e.header("x-grok-turn-idx").is_some());
+        .partition(|e| e.header("x-kigi-turn-idx").is_some());
     assert!(
         !turns.is_empty(),
         "no session turn POST /v1/responses logged; requests:\n{}",
@@ -580,7 +580,7 @@ async fn headless_config_enables_doom_loop_check_header() {
     );
     for turn in turns {
         assert_eq!(
-            turn.header("x-grok-doom-loop-check"),
+            turn.header("x-kigi-doom-loop-check"),
             Some("true"),
             "[doom_loop_recovery] enabled must reach the turn request header; requests:\n{}",
             server.request_log_summary()
@@ -588,7 +588,7 @@ async fn headless_config_enables_doom_loop_check_header() {
     }
     for side_query in aux {
         assert_eq!(
-            side_query.header("x-grok-doom-loop-check"),
+            side_query.header("x-kigi-doom-loop-check"),
             None::<&str>,
             "the session policy must not leak into aux side-query clients; requests:\n{}",
             server.request_log_summary()