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test could previously reach the real api.moonshot.cn), and the outdated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

@@ -104,13 +104,13 @@ mod tests {
     fn turn_started_round_trip() {
         let event = SessionEvent::TurnStarted {
             turn_number: 1,
-            model_id: "grok-3".into(),
+            model_id: "kigi-3".into(),
             yolo_mode: true,
         };
         let v = serde_json::to_value(&event).unwrap();
         assert_eq!(v["event_type"], "turn_started");
         assert_eq!(v["turn_number"], 1);
-        assert_eq!(v["model_id"], "grok-3");
+        assert_eq!(v["model_id"], "kigi-3");
         assert_eq!(v["yolo_mode"], true);
         let back: SessionEvent = serde_json::from_value(v).unwrap();
         assert_eq!(back, event);
@@ -121,14 +121,14 @@ mod tests {
         let v = json!({
             "event_type": "turn_started",
             "turn_number": 5,
-            "model_id": "grok-3",
+            "model_id": "kigi-3",
         });
         let event: SessionEvent = serde_json::from_value(v).unwrap();
         assert_eq!(
             event,
             SessionEvent::TurnStarted {
                 turn_number: 5,
-                model_id: "grok-3".into(),
+                model_id: "kigi-3".into(),
                 yolo_mode: false,
             }
         );
@@ -141,7 +141,7 @@ mod tests {
             outcome: TurnHookOutcome::Completed,
             duration_ms: 2500,
             tool_call_count: 7,
-            model_id: "grok-3".into(),
+            model_id: "kigi-3".into(),
         };
         let v = serde_json::to_value(&event).unwrap();
         assert_eq!(v["event_type"], "turn_ended");
@@ -342,7 +342,7 @@ mod tests {
         let v = json!({
             "event_type": "turn_started",
             "turn_number": 1,
-            "model_id": "grok-3",
+            "model_id": "kigi-3",
             "future_field": "should be ignored",
         });
         let event: SessionEvent = serde_json::from_value(v).unwrap();
@@ -350,7 +350,7 @@ mod tests {
             event,
             SessionEvent::TurnStarted {
                 turn_number: 1,
-                model_id: "grok-3".into(),
+                model_id: "kigi-3".into(),
                 yolo_mode: false,
             }
         );
@@ -365,7 +365,7 @@ mod tests {
             "turn_number": 1,
             "duration_ms": 100,
             "tool_call_count": 0,
-            "model_id": "grok-3",
+            "model_id": "kigi-3",
             // missing "outcome"
         });
         assert!(serde_json::from_value::<SessionEvent>(v).is_err());