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test could previously reach the real api.moonshot.cn), and the outdated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

@@ -62,7 +62,7 @@ pub(super) fn immediate_server_send_eligible(agent: &AgentView) -> bool {
 
 /// Push the optimistic shared-queue echo for an immediate server-authoritative
 /// send and mirror it into the owning agent so the queue pane renders it
-/// immediately, before the confirming `x.ai/queue/changed` broadcast.
+/// immediately, before the confirming `kigi/queue/changed` broadcast.
 pub(super) fn push_server_queue_echo(
     app: &mut AppView,
     agent_id: AgentId,
@@ -91,7 +91,7 @@ pub(super) fn push_server_queue_echo(
 ///
 /// The agent's `pending_inputs` is the single source of truth for queue
 /// contents and order; the only client-side queue state is the optimistic echo
-/// that bridges the round-trip before the confirming `x.ai/queue/changed`
+/// that bridges the round-trip before the confirming `kigi/queue/changed`
 /// broadcast. Once a prompt's RPC resolves (or we pull it back into the input
 /// on cancel) it will never reappear in a future broadcast, so its echo must be
 /// dropped — otherwise the reconcile in [`AppView::apply_queue_changed`] keeps
@@ -633,7 +633,7 @@ pub(crate) fn apply_turn_start_shim(
     agent.session.current_prompt_id = Some(prompt_id.clone());
     agent.attached_as_viewer = adopted_from_other_client;
     // A new (adopted) turn is starting: drop the prior turn's chips but KEEP the
-    // seen ring, so a buffer-replayed `x.ai/follow_ups` for an older response
+    // seen ring, so a buffer-replayed `kigi/follow_ups` for an older response
     // stays rejected (no stale revival). This is correct for BOTH passive-viewer
     // and self-driven adoption: the adopted turn's OWN follow_ups still
     // re-render via the stamped `promptId` match in `apply_follow_ups` (the
@@ -1150,7 +1150,7 @@ mod tests {
     }
 
     /// FIX 4 (b) via the shim: after starting a NEW turn, a buffer-replayed
-    /// `x.ai/follow_ups` for a PRIOR turn's response stays rejected (its
+    /// `kigi/follow_ups` for a PRIOR turn's response stays rejected (its
     /// `promptId` is not the active turn and it is already seen) — no stale
     /// revival. Covers the self-driven turn start (`p-self`).
     #[test]