§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test could previously reach the real api.moonshot.cn), and the outdated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-tools-api/tests/wire_shape.rs

@@ -9,7 +9,7 @@ use kigi_tools_api::ToolConfigEntry;
 
 fn full_entry() -> ToolConfigEntry {
     ToolConfigEntry {
-        id: "GrokBuild:grep".to_owned(),
+        id: "Kigi:grep".to_owned(),
         params_json: Some(r#"{"max_results":50}"#.to_owned()),
         name_override: Some("search".to_owned()),
         params_name_overrides: std::collections::HashMap::from([(
@@ -27,7 +27,7 @@ fn tool_config_entry_serializes_to_pinned_json_shape() {
     assert_eq!(
         value,
         serde_json::json!({
-            "id": "GrokBuild:grep",
+            "id": "Kigi:grep",
             "params_json": "{\"max_results\":50}",
             "name_override": "search",
             "params_name_overrides": {"pattern": "query"},
@@ -48,10 +48,9 @@ fn tool_config_entry_round_trips() {
 #[test]
 fn minimal_entry_deserializes_from_id_only() {
     // Consumers must accept sparse payloads: optional fields absent, map empty.
-    let back: ToolConfigEntry =
-        serde_json::from_value(serde_json::json!({"id": "GrokBuild:read_file"}))
-            .expect("deserialize minimal");
-    assert_eq!(back.id, "GrokBuild:read_file");
+    let back: ToolConfigEntry = serde_json::from_value(serde_json::json!({"id": "Kigi:read_file"}))
+        .expect("deserialize minimal");
+    assert_eq!(back.id, "Kigi:read_file");
     assert_eq!(back.params_json, None);
     assert_eq!(back.name_override, None);
     assert!(back.params_name_overrides.is_empty());
@@ -73,7 +72,7 @@ fn explicit_null_optional_fields_deserialize_as_none() {
     // `#[serde(default)]` covers *absent* keys; explicit `null` is handled by
     // the `Option` fields themselves. Pin that both shapes are accepted.
     let back: ToolConfigEntry = serde_json::from_value(serde_json::json!({
-        "id": "GrokBuild:read_file",
+        "id": "Kigi:read_file",
         "params_json": null,
         "name_override": null,
         "behavior_version": null,
@@ -92,7 +91,7 @@ fn explicit_null_map_is_rejected() {
     // map. Producers must omit the key or emit `{}`. Pin the rejection so a
     // codegen change that silently starts accepting `null` is caught.
     let result: Result<ToolConfigEntry, _> = serde_json::from_value(serde_json::json!({
-        "id": "GrokBuild:read_file",
+        "id": "Kigi:read_file",
         "params_name_overrides": null,
     }));
     assert!(