§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test could previously reach the real api.moonshot.cn), and the outdated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/common/kigi-tool-protocol/tests/identifier_validation.rs

@@ -12,8 +12,8 @@ fn tool_id_accepts_bare_and_namespaced_names() {
     let bare = ToolId::new("read_file").unwrap();
     assert_eq!(bare.as_str(), "read_file");
 
-    let namespaced = ToolId::new("GrokBuild:read_file").unwrap();
-    assert_eq!(namespaced.as_str(), "GrokBuild:read_file");
+    let namespaced = ToolId::new("Kigi:read_file").unwrap();
+    assert_eq!(namespaced.as_str(), "Kigi:read_file");
 
     assert_eq!(
         ToolId::from_str("github:list_repos").unwrap().as_str(),
@@ -81,8 +81,8 @@ fn tool_id_rejects_empty_segments_around_separator() {
 
 #[test]
 fn tool_id_try_from_string_works() {
-    let id: ToolId = "GrokBuild:read_file".to_owned().try_into().unwrap();
-    assert_eq!(id.as_str(), "GrokBuild:read_file");
+    let id: ToolId = "Kigi:read_file".to_owned().try_into().unwrap();
+    assert_eq!(id.as_str(), "Kigi:read_file");
 }
 
 #[test]
@@ -116,15 +116,15 @@ fn server_id_synthesis_starts_with_auto_prefix() {
     let synth = ServerId::synthesize_for_tool(&conn, &bare);
     assert_eq!(synth.as_str(), "auto:tool:read_file");
 
-    let namespaced = ToolId::new("GrokBuild:read_file").unwrap();
+    let namespaced = ToolId::new("Kigi:read_file").unwrap();
     let synth_ns = ServerId::synthesize_for_tool(&conn, &namespaced);
-    assert_eq!(synth_ns.as_str(), "auto:tool:GrokBuild:read_file");
+    assert_eq!(synth_ns.as_str(), "auto:tool:Kigi:read_file");
 }
 
 #[test]
 fn server_id_synthesis_is_deterministic() {
     let conn = ConnectionId::new("conn-abc").unwrap();
-    let tool = ToolId::new("GrokBuild:read_file").unwrap();
+    let tool = ToolId::new("Kigi:read_file").unwrap();
     let a = ServerId::synthesize_for_tool(&conn, &tool);
     let b = ServerId::synthesize_for_tool(&conn, &tool);
     assert_eq!(