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test could previously reach the real api.moonshot.cn), and the outdated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

@@ -4445,7 +4445,7 @@ pub fn load_persisted_from_path(path: &std::path::Path) -> Option<PersistedDashb
 /// + rename, so concurrent readers never observe a half-truncated file.
 pub fn write_persisted(p: &PersistedDashboard) -> std::io::Result<()> {
     let path = config_path()
-        .ok_or_else(|| std::io::Error::new(std::io::ErrorKind::NotFound, "no grok home"))?;
+        .ok_or_else(|| std::io::Error::new(std::io::ErrorKind::NotFound, "no kigi home"))?;
     write_persisted_to_path(&path, p)
 }
 
@@ -4788,8 +4788,8 @@ mod tests {
 
     #[test]
     fn compact_cwd_strips_home() {
-        let p = Path::new("/Users/alice/projects/grok");
-        assert_eq!(compact_cwd(p, Some("/Users/alice")), "~/projects/grok");
+        let p = Path::new("/Users/alice/projects/kigi");
+        assert_eq!(compact_cwd(p, Some("/Users/alice")), "~/projects/kigi");
     }
 
     #[test]