§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test could previously reach the real api.moonshot.cn), and the outdated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/docs/user-guide/04-slash-commands.md

@@ -40,7 +40,7 @@ Compress conversation history to save context window space. Optionally specify w
 /compact keep the auth implementation details
 ```
 
-When the context window fills up, Grok auto-compacts at 85% usage (configurable via `[session] auto_compact_threshold_percent` in config.toml).
+When the context window fills up, Kigi auto-compacts at 85% usage (configurable via `[session] auto_compact_threshold_percent` in config.toml).
 
 ### `/context`
 
@@ -131,8 +131,8 @@ Aliases: `/title`
 Switch to a different model. Accepts model IDs or display names (case-insensitive). For reasoning models you can also pass an effort level as a second argument:
 
 ```
-/model grok-build
-/model Grok Build
+/model kigi
+/model Kigi
 /model Reasoning X high
 ```
 
@@ -214,7 +214,7 @@ fullscreen) switches to the experimental scrollback-native mode; `/fullscreen`
 TUI. Both relaunch the pager on the same conversation for this session only —
 they do not write `config.toml`. Descriptions and the relaunch banner tell you
 how to switch back (`/fullscreen` ⇄ `/minimal`). The `--minimal` /
-`--fullscreen` CLI flags are likewise session-scoped. To make plain `grok` open
+`--fullscreen` CLI flags are likewise session-scoped. To make plain `kigi` open
 in a given mode by default, use `/settings` → **Default screen mode**, or set
 `[ui] screen_mode` in `config.toml`.
 
@@ -325,7 +325,7 @@ Open the extensions modal on the Skills tab to view installed skills.
 
 ### `/loop [interval] <prompt>`
 
-Run a prompt on a recurring interval. Specify the interval as `30m`, `1 hour`, or `every 2 days`. If you omit it, Grok prompts you.
+Run a prompt on a recurring interval. Specify the interval as `30m`, `1 hour`, or `every 2 days`. If you omit it, Kigi prompts you.
 
 ```
 /loop 30m check deploy status
@@ -342,7 +342,7 @@ Recurring tasks auto-expire after 7 days. Cancel with `scheduler_delete` (the jo
 
 ### `/goal`
 
-Set, manage, or check an autonomous goal. Grok works toward the objective across turns and reports progress.
+Set, manage, or check an autonomous goal. Kigi works toward the objective across turns and reports progress.
 
 ```
 /goal Migrate the auth module to the new API