§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test could previously reach the real api.moonshot.cn), and the outdated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/slash/commands/docs.rs

@@ -1,15 +1,16 @@
-//! `/docs` -- open How-to Guides (in-TUI) or online Build docs.
+//! `/docs` -- open How-to Guides (in-TUI) or the online docs.
 //!
 //! Bare `/docs` opens the same DocPicker as command-palette "How-to Guides".
-//! `/docs web` opens https://docs.x.ai/build/overview in the browser.
+//! `/docs web` opens the Kigi project docs in the browser.
 //! `/docs <title>` opens a single guide by title (case-insensitive).
 
 use crate::app::actions::Action;
 use crate::docs::{all_titles, find_doc};
 use crate::slash::command::{AppCtx, ArgItem, CommandExecCtx, CommandResult, SlashCommand};
 
-/// Online Build docs landing page (hardcoded like other TUI deep-links; docs.x.ai can redirect if the path moves).
-pub const BUILD_DOCS_URL: &str = "https://docs.x.ai/build/overview";
+/// Online docs landing page (hardcoded like other TUI deep-links; the
+/// project README is the docs entry point for the GitHub-hosted docs).
+pub const BUILD_DOCS_URL: &str = "https://github.com/ZacharyZhang-NY/Kigi-CLI#readme";
 
 /// Open How-to Guides or online Build docs.
 pub struct DocsCommand;
@@ -55,7 +56,7 @@ impl SlashCommand for DocsCommand {
                 display: "web".into(),
                 match_text: "web".into(),
                 insert_text: "web".into(),
-                description: "Open docs.x.ai/build in the browser".into(),
+                description: "Open docs.kigi/build in the browser".into(),
             },
         ];
         items.extend(all_titles().map(|title| ArgItem {