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test could previously reach the real api.moonshot.cn), and the outdated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

@@ -38,7 +38,7 @@
                 "token_baseline": 100,
                 "finished_subagent_tokens": 99,
                 "live_subagent_tokens": 4_321,
-                "live_tokens_by_model": [["grok-4", 6_000], ["grok-3", 4_000]],
+                "live_tokens_by_model": [["kigi-4", 6_000], ["kigi-3", 4_000]],
                 "live_context_pct": 42,
                 "live_turn_count": 7,
                 "live_tool_call_count": 11,
@@ -54,7 +54,7 @@
             }
         });
         let raw = serde_json::value::to_raw_value(&raw_payload).unwrap();
-        let request = acp::ExtNotification::new("x.ai/session_notification", raw.into());
+        let request = acp::ExtNotification::new("kigi/session_notification", raw.into());
         let (tx, _rx) = tokio::sync::oneshot::channel();
         let msg = AcpClientMessage::ExtNotification(kigi_acp_lib::AcpArgs {
             request,
@@ -94,7 +94,7 @@
         assert_eq!(goal.live_subagent_tokens, Some(4_321));
         assert_eq!(
             goal.live_tokens_by_model,
-            vec![("grok-4".to_owned(), 6_000), ("grok-3".to_owned(), 4_000)],
+            vec![("kigi-4".to_owned(), 6_000), ("kigi-3".to_owned(), 4_000)],
             "populated per-model breakdown must round-trip wire->display"
         );
         assert_eq!(goal.live_context_pct, Some(42));
@@ -147,7 +147,7 @@
             let (tx, _rx) = tokio::sync::oneshot::channel();
             handle(
                 AcpClientMessage::ExtNotification(kigi_acp_lib::AcpArgs {
-                    request: acp::ExtNotification::new("x.ai/session_notification", raw.into()),
+                    request: acp::ExtNotification::new("kigi/session_notification", raw.into()),
                     response_tx: tx,
                 }),
                 app,
@@ -372,7 +372,7 @@
             }
         });
         let raw = serde_json::value::to_raw_value(&raw_payload).unwrap();
-        let request = acp::ExtNotification::new("x.ai/session_notification", raw.into());
+        let request = acp::ExtNotification::new("kigi/session_notification", raw.into());
         let (tx, _rx) = tokio::sync::oneshot::channel();
         let msg = AcpClientMessage::ExtNotification(kigi_acp_lib::AcpArgs {
             request,