M0: compilable skeleton — Kigi 0.1.0 fork surgery

Hard fork of xai-org/grok-build (Apache-2.0) re-targeted as Kigi, an
unofficial Kimi Code CLI community build.

Rename & identity
- 72 xai-*/xai-grok-* crates -> kigi-* (explicit: xai-grok-pager-bin ->
  kigi-bin [binary `kigi`], xai-grok-pager -> kigi-tui; rest mechanical);
  ptyctl, ptyctl-cli, third_party/ unchanged; proto package
  xai.grok.tools.v1 -> kigi.tools.v1
- Config home ~/.kigi (KIGI_SHARE_DIR override), env prefix GROK_* ->
  KIGI_*, `kigi --version` carries the unofficial-community-build notice
- clap identity, help text, startup banner, prompt templates rebranded
  (templates re-encrypted)

Deletions (PRD removal list #5/#6/#7/#9/#10)
- voice input (xai-grok-voice) and all TUI wiring
- telemetry: Mixpanel client, external OTel stream, Sentry, OTLP layers,
  trace/GCS/S3 upload queues (kigi-file-utils halved), workspace upload
  module & dc_log, heap-profile uploader, auth-diagnostics uploader,
  session-analytics halves of feedback; local zero-egress observability
  preserved in new kigi-log crate (unified log, --debug firehose,
  subsystem file logs, opt-in instrumentation)
- announcements (crate, remote-settings fields, TUI surfaces)
- plugin marketplace (crate, sources/browse/CTA/extensions-modal tab);
  direct plugin install/uninstall/update via kigi-agent git_install kept
- relay/gateway/assets endpoints and features (agent relay, headless
  relay transport, gateway bridge, LeaderEnvUrls); leader IPC socket now
  ~/.kigi/leader.sock + KIGI_LEADER_SOCKET, no ws-url derivation
- functional types rehomed instead of deleted: PermissionMode ->
  kigi-config-types, McpInitStrategy -> kigi-mcp, PrCreationSource ->
  session signals, TerminalDiagnostics -> kigi-pager-render, agent_id ->
  shell util

Endpoints
- kigi-env rewritten: single production KigiEndpoints {coding_api_base_url
  https://api.kimi.com/coding/v1 (KIGI_CODE_BASE_URL), oauth_host
  https://auth.kimi.com (KIGI_OAUTH_HOST), update_base_url (GitHub
  Releases API), upgrade_page_url}; GrokBuildEnvironment enum deleted

Toolchain & workspace hygiene
- Rust 1.97.0 pinned; edition 2024; full cargo update; git2 hoisted to
  workspace at 0.21 (Option->Result API migration), quick-xml 0.41
- Root Cargo.toml hand-maintained (PRD §8.1): version 0.1.0 inherited by
  all members, members sorted, unused deps pruned
- cargo-deny advisories gate (deny.toml with documented transitive
  exceptions); CI workflow (check/clippy/fmt/deny/test, macOS+Linux)
- cross-crate test seams re-gated behind `test-support` cargo feature;
  insta snapshot baselines renamed to the kigi_tui prefix
- clippy --workspace --all-targets: zero warnings; fmt clean

Fixes surfaced by the port
- updater probe/installer divergence (bin/kigi vs bin/grok symlink set)
- idle model-metadata refresh dead under KIGI_CODE_BASE_URL override
  (new is_effective_coding_endpoint_url, loopback+override aware)
- macOS symlinked-TMPDIR fixture canonicalization (foreign_sessions,
  fast-worktree); RSS measurement tests serialized via serial_test

Docs & legal (Apache §4)
- NOTICE added (upstream attribution + change statement); THIRD-PARTY
  notices sustained; kigi-tools ported-code notices extended; README,
  CONTRIBUTING, SECURITY, AGENTS.md rewritten

Out of scope for M0 (tracked): Kimi auth/inference (M1), search/fetch,
command parity, config import (M2), Computer Hub excision & final
brand-token sweep (M2), distribution & self-update rewrite (M3).

crates/codegen/kigi-shell/src/extensions/mod.rs

@@ -0,0 +1,87 @@
+pub mod auth;
+pub(crate) mod auth_gate;
+pub mod billing;
+pub mod bundle;
+pub mod chat_conversation_history;
+pub mod code_nav;
+pub mod debug;
+pub mod feedback;
+pub mod fs;
+pub mod git;
+pub mod hooks;
+pub mod hunk_tracker;
+pub mod interject;
+pub mod jj;
+pub mod mcp;
+pub mod memory;
+pub mod notification;
+pub mod plugins;
+pub mod pr;
+pub mod privacy;
+pub mod prompt_history;
+pub mod prompt_meta;
+pub mod recap;
+pub mod repair;
+pub mod rewind;
+pub mod rollout;
+pub mod routing;
+pub mod search;
+pub mod session_admin;
+pub mod session_search;
+pub mod session_updates;
+pub mod share;
+pub mod skills;
+pub mod suggest;
+pub mod task;
+pub mod terminal;
+pub mod worktree;
+use crate::session::ExtMethodResult;
+use agent_client_protocol as acp;
+use serde::Serialize;
+use serde::de::DeserializeOwned;
+use std::sync::Arc;
+pub type ExtResult = Result<acp::ExtResponse, acp::Error>;
+pub fn parse_params<T: DeserializeOwned>(args: &acp::ExtRequest) -> Result<T, acp::Error> {
+    parse_params_str(args.params.get())
+}
+/// Deserialize ACP params from their raw JSON string, mapping a parse failure
+/// to `invalid_params`. Used by [`parse_params`] and the bridge `encode` hooks,
+/// which hold the params `RawValue` directly.
+pub fn parse_params_str<T: DeserializeOwned>(raw: &str) -> Result<T, acp::Error> {
+    serde_json::from_str(raw)
+        .map_err(|e| acp::Error::invalid_params().data(format!("invalid params: {}", e)))
+}
+/// Extract the session ID from an extension request's params.
+pub fn parse_session_id(args: &acp::ExtRequest) -> Option<acp::SessionId> {
+    let v: serde_json::Value = serde_json::from_str(args.params.get()).ok()?;
+    let sid = v.get("sessionId")?.as_str()?;
+    Some(acp::SessionId::new(sid))
+}
+pub fn to_ext_response<T: Serialize>(result: anyhow::Result<T>) -> ExtResult {
+    ExtMethodResult::from_result(result)
+        .to_ext_response()
+        .map_err(|e| acp::Error::internal_error().data(e.to_string()))
+}
+/// Wrap a serializable value as an `ExtResponse` without the `ExtMethodResult` envelope.
+pub fn to_raw_response<T: Serialize>(v: &T) -> ExtResult {
+    serde_json::value::to_raw_value(v)
+        .map(|raw| acp::ExtResponse::new(Arc::from(raw)))
+        .map_err(|e| acp::Error::internal_error().data(e.to_string()))
+}
+/// Convert a result with optional warning to an ExtResponse.
+pub fn to_ext_response_partial<T: Serialize>(
+    result: anyhow::Result<T>,
+    warning: Option<String>,
+) -> ExtResult {
+    let ext_result = match (result, warning) {
+        (Ok(data), Some(warn)) => ExtMethodResult::partial(data, warn),
+        (Ok(data), None) => ExtMethodResult::success(data),
+        (Err(e), _) => ExtMethodResult::failure(e),
+    };
+    ext_result
+        .to_ext_response()
+        .map_err(|e| acp::Error::internal_error().data(e.to_string()))
+}
+/// Empty response for operations that return no data.
+#[derive(Debug, Serialize)]
+pub struct Empty {}