§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test could previously reach the real api.moonshot.cn), and the outdated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-mcp/src/acp_transport.rs

@@ -1,9 +1,9 @@
 //! rmcp transport bridge over the ACP reverse channel.
 //!
-//! In-process SDK MCP servers (the official `grok-agent-sdk`'s `@tool` /
+//! In-process SDK MCP servers (the official `kigi-agent-sdk`'s `@tool` /
 //! `create_sdk_mcp_server`) run in the SDK-host process, not behind a socket. The
 //! agent reaches them by sending each MCP JSON-RPC message to the client as a
-//! reverse `x.ai/mcp/sdk_call` request and feeding the response back. This module
+//! reverse `kigi/mcp/sdk_call` request and feeding the response back. This module
 //! adapts that request/response channel into an rmcp transport so an in-process
 //! server reuses the same `RunningService` / tool-dispatch path as HTTP/stdio
 //! servers for tool calls.
@@ -28,7 +28,7 @@ use serde_json::Value;
 use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader, DuplexStream};
 
 /// Sends one MCP JSON-RPC message to an in-process server over the ACP reverse
-/// channel (`x.ai/mcp/sdk_call`) and returns its JSON-RPC response. The `Err` string is
+/// channel (`kigi/mcp/sdk_call`) and returns its JSON-RPC response. The `Err` string is
 /// surfaced as a JSON-RPC error to the waiting rmcp request (fail-closed: a missing
 /// tool server is a real error, unlike a hook gate).
 ///
@@ -65,7 +65,7 @@ const INTERNAL_ERROR_CODE: i64 = -32603;
 /// Build an rmcp transport that bridges to an in-process MCP server via `invoker`.
 ///
 /// Spawns a pump that forwards each client→server message as a reverse
-/// `x.ai/mcp/sdk_call` and writes the server→client response back. The pump exits when
+/// `kigi/mcp/sdk_call` and writes the server→client response back. The pump exits when
 /// rmcp drops its half of the duplex (service shutdown), so it never leaks.
 ///
 /// `invoke_timeout` is the resolved per-server tool timeout; it bounds every reverse
@@ -159,7 +159,7 @@ async fn read_requests(
             }
         };
         // An id-less message is a notification (no response). The SDK peer rejects reverse
-        // `x.ai/mcp/sdk_call`s without a JSON-RPC id, so id-less messages (e.g. rmcp's
+        // `kigi/mcp/sdk_call`s without a JSON-RPC id, so id-less messages (e.g. rmcp's
         // `notifications/initialized` on every handshake) are logged and discarded locally
         // rather than spawning a doomed round-trip. Safe only because the SDK `Server` is
         // lenient about never receiving `initialized` (a documented v1 limit).