§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test could previously reach the real api.moonshot.cn), and the outdated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-pager-render/src/appearance/config.rs

@@ -1715,7 +1715,7 @@ fn parse_hex_color(hex: &str) -> Result<Color, String> {
 }
 
 fn lookup_named_color(name: &str) -> Result<Color, String> {
-    // Named colors use the GrokNight RGB palette. They are quantized via
+    // Named colors use the KigiNight RGB palette. They are quantized via
     // `parse_color_string` → `quantize()` to match the terminal's capabilities.
     let color = match name.to_uppercase().as_str() {
         // Background colors
@@ -1787,10 +1787,10 @@ impl RawAppearanceConfig {
         let toml_str = toml_edit::ser::to_string_pretty(&config).expect("serialize default");
         let mut doc: DocumentMut = toml_str.parse().expect("parse toml");
 
-        let pager_path = crate::util::display_user_grok_path("pager.toml");
+        let pager_path = crate::util::display_user_kigi_path("pager.toml");
         let header = format!(
             "\
-# Grok Pager Appearance Configuration ({pager_path})
+# Kigi Pager Appearance Configuration ({pager_path})
 # Every value below is a commented-out built-in default: uncomment a line and
 # save to override it. Values left commented track future default changes.
 # Delete the file to regenerate this template.
@@ -1935,7 +1935,7 @@ pub fn persist_respect_manual_folds(enabled: bool) -> std::io::Result<()> {
     if kigi_config::user_kigi_home().is_none() {
         return Err(Error::new(
             ErrorKind::NotFound,
-            "no user grok home resolved; refusing to write a cwd-relative pager.toml \
+            "no user kigi home resolved; refusing to write a cwd-relative pager.toml \
              that startup would never read",
         ));
     }