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test could previously reach the real api.moonshot.cn), and the outdated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

@@ -6,8 +6,8 @@
 //! stay in each product host (for example `kigi-shell`).
 //!
 //! The crate depends on **neither** a conversation-type crate nor
-//! `kigi-sampling-types`. It is decoupled from both Grok chat and
-//! grok-build hosts through a small set of trait seams:
+//! `kigi-sampling-types`. It is decoupled from both Kigi chat and
+//! kigi hosts through a small set of trait seams:
 //!
 //! - [`CompactionItem`] / [`CompactionRole`] / [`CompactionItemBuilder`] —
 //!   abstracts a single turn and its reconstruction.
@@ -21,10 +21,10 @@
 //!
 //! Compaction styles live in their own modules:
 //!
-//! - [`code_compaction`] — grok-build's whole-session **full-replace**
+//! - [`code_compaction`] — kigi's whole-session **full-replace**
 //!   subsystem (prompt/summary/failure/config, assemble, orchestration).
-//! - [`intra_compaction`] — Grok chat's tail-keep, per-step pass.
-//! - [`inter_compaction`] — Grok chat's chunked, between-turn pass.
+//! - [`intra_compaction`] — Kigi chat's tail-keep, per-step pass.
+//! - [`inter_compaction`] — Kigi chat's chunked, between-turn pass.
 //!
 //! Compaction-type content (parallel subfolders): [`steps`] (the step-level
 //! prompt) and [`history`] (filtering, history prompts, validation +
@@ -34,8 +34,8 @@
 //! [`prompt::CompactionPrompt`], [`select`] (tool-pair-safe tail-keep
 //! selection — shared by the intra `Steps` and `History` targets, so it stays
 //! neutral at the crate root rather than under `steps`), and [`reminder`]
-//! (active-agent-state `<system-reminder>` formatting shared by Grok chat and
-//! grok-build; hosts still own snapshotting and host-only sections).
+//! (active-agent-state `<system-reminder>` formatting shared by Kigi chat and
+//! kigi; hosts still own snapshotting and host-only sections).
 
 pub mod code_compaction;
 pub mod history;
@@ -57,7 +57,7 @@ pub mod token;
 /// 3. this constant
 pub use intra_compaction::DEFAULT_COMPACTION_MODEL_NAME;
 
-// grok-build's full-replace subsystem now lives under `code_compaction`;
+// kigi's full-replace subsystem now lives under `code_compaction`;
 // re-exported at the crate root so consumers keep a stable public API.
 pub use code_compaction::{
     CompactedHistoryParts, DEFAULT_AUTO_COMPACT_THRESHOLD_PERCENT, FailureKind,