§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test could previously reach the real api.moonshot.cn), and the outdated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-shell/src/session/helpers/full_replace_compaction.rs

@@ -1,9 +1,9 @@
-//! grok-build's L5 wiring onto the shared full-replace engine
+//! kigi's L5 wiring onto the shared full-replace engine
 //! (`kigi_compaction::code_compaction`).
 //!
 //! The shared engine drives the sample → retry → degenerate/failure
 //! classification loop via [`sample_full_replace_summary`](kigi_compaction::sample_full_replace_summary);
-//! this module adapts grok-build's transport and telemetry to its two seams:
+//! this module adapts kigi's transport and telemetry to its two seams:
 //!
 //! - [`ShellCompactionSampler`] wraps
 //!   [`generate_session_compact`](crate::session::helpers::session_compact::generate_session_compact)
@@ -42,7 +42,7 @@ use crate::session::helpers::session_compact::{
 };
 
 /// Wraps `generate_session_compact` as the shared engine's
-/// [`CompactionSampler`] for grok-build's full-replace pass.
+/// [`CompactionSampler`] for kigi's full-replace pass.
 ///
 /// Holds the per-call request context the seam does not carry (tools, client,
 /// session, config) and stashes the last successful [`CompactOutput`] so the
@@ -51,8 +51,8 @@ use crate::session::helpers::session_compact::{
 ///
 /// The summarization prompt is selected here by `use_short_prompt` (the
 /// short-prompt harness uses the short self-summarization prompt; everyone
-/// else the structured grok-build prompt), so the shared `CompactionPrompt`
-/// the engine passes is ignored — the engine builds the grok-build prompt,
+/// else the structured kigi prompt), so the shared `CompactionPrompt`
+/// the engine passes is ignored — the engine builds the kigi prompt,
 /// which equals what `build_compaction_chat_history(.., false)` appends, and
 /// the short-prompt harness needs its own variant the engine can't produce.
 pub(crate) struct ShellCompactionSampler {
@@ -118,7 +118,7 @@ impl CompactionSampler for ShellCompactionSampler {
         _timeout: Duration,
     ) -> Result<LlmCompactionOutput, CompactionSampleError> {
         // Append the harness-selected summarization prompt as the final user
-        // message (compat short vs structured grok-build), ignoring the shared
+        // message (compat short vs structured kigi), ignoring the shared
         // engine's `_prompt` (see the struct doc).
         let chat_history = build_compaction_chat_history(
             turns.to_vec(),
@@ -151,7 +151,7 @@ impl CompactionSampler for ShellCompactionSampler {
     }
 }
 
-/// Map grok-build's [`CompactFailure`] onto the shared engine's
+/// Map kigi's [`CompactFailure`] onto the shared engine's
 /// [`CompactionSampleError`] so the shared retry loop classifies it the same
 /// way the in-shell loop did:
 ///
@@ -207,7 +207,7 @@ struct ObserverState {
     last_error_msg: Option<String>,
 }
 
-/// [`FullReplaceObserver`] that reproduces grok-build's per-attempt telemetry:
+/// [`FullReplaceObserver`] that reproduces kigi's per-attempt telemetry:
 /// `CompactionAttempt` rows, rejection counters, the `CompactionRetryDegraded`
 /// event, and the warn/error tracing — without the shared engine depending on
 /// a telemetry backend.