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test could previously reach the real api.moonshot.cn), and the outdated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

@@ -1,4 +1,4 @@
-//! `x.ai/feedback`, `x.ai/feedback/dismiss`, `x.ai/btw`, and `x.ai/review/*`
+//! `kigi/feedback`, `kigi/feedback/dismiss`, `kigi/btw`, and `kigi/review/*`
 //! extension handlers.
 //!
 //! - `feedback`/`feedback/dismiss`: persist user ratings/text locally; text
@@ -28,15 +28,15 @@ use crate::session::{
 #[tracing::instrument(skip_all, fields(method = %args.method))]
 pub async fn handle(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtResult {
     match args.method.as_ref() {
-        "x.ai/btw" => {
+        "kigi/btw" => {
             tracing::info!("handling /btw side question");
             handle_btw(agent, args).await
         }
-        "x.ai/feedback" | "x.ai/feedback/dismiss" => {
+        "kigi/feedback" | "kigi/feedback/dismiss" => {
             tracing::info!("handling user feedback");
             handle_feedback(agent, args).await
         }
-        m if m.starts_with("x.ai/review") => {
+        m if m.starts_with("kigi/review") => {
             tracing::info!("handling review comment");
             handle_review(args).await
         }
@@ -44,7 +44,7 @@ pub async fn handle(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtResult {
     }
 }
 
-/// Handle `x.ai/btw` -- a side question that doesn't interrupt the current turn.
+/// Handle `kigi/btw` -- a side question that doesn't interrupt the current turn.
 async fn handle_btw(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtResult {
     #[derive(serde::Deserialize)]
     #[serde(rename_all = "camelCase")]
@@ -89,7 +89,7 @@ async fn handle_feedback(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtResult
     }
 
     match args.method.as_ref() {
-        "x.ai/feedback" => {
+        "kigi/feedback" => {
             // Parse the input -- try the full ClientFeedbackInput first,
             // then fall back to the simple FeedbackRequest (from /feedback slash command)
             // which only has {session_id, feedback_text} and no client_type.
@@ -245,7 +245,7 @@ async fn handle_feedback(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtResult
                 .expect("to work");
             Ok(acp::ExtResponse::new(value))
         }
-        "x.ai/feedback/dismiss" => {
+        "kigi/feedback/dismiss" => {
             let dismiss_input: FeedbackRequestDismiss = parse_params(args)?;
 
             tracing::info!(
@@ -302,11 +302,11 @@ async fn handle_feedback(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtResult
 /// Record inline code review events.
 ///
 /// Methods:
-/// - `x.ai/review/comment`: record a new inline code comment
-/// - `x.ai/review/comment/delete`: record a tombstone event for a deleted comment
+/// - `kigi/review/comment`: record a new inline code comment
+/// - `kigi/review/comment/delete`: record a tombstone event for a deleted comment
 async fn handle_review(args: &acp::ExtRequest) -> ExtResult {
     match args.method.as_ref() {
-        "x.ai/review/comment" => {
+        "kigi/review/comment" => {
             let request: CommentRequest = parse_params(args)?;
 
             let comment_id = uuid::Uuid::now_v7().to_string();
@@ -329,7 +329,7 @@ async fn handle_review(args: &acp::ExtRequest) -> ExtResult {
             .expect("to work");
             Ok(acp::ExtResponse::new(value))
         }
-        "x.ai/review/comment/delete" => {
+        "kigi/review/comment/delete" => {
             let request: CommentDeleteRequest = parse_params(args)?;
 
             tracing::info!(