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-log/src/appender.rs

@@ -0,0 +1,46 @@
+//! Shared non-blocking file appender + worker-guard registry for telemetry file-log layers.
+
+use std::path::Path;
+use std::sync::{Mutex, OnceLock};
+
+use tracing_appender::non_blocking::{NonBlocking, WorkerGuard};
+
+// Park every worker guard for process lifetime; dropping a guard flushes and
+// shuts down that file's writer thread, so accumulate (never overwrite) to let
+// multiple file-log layers coexist.
+static FILE_LOG_GUARDS: OnceLock<Mutex<Vec<WorkerGuard>>> = OnceLock::new();
+
+/// Shared non-blocking file writer for telemetry file-log layers. Opens `path`
+/// in append mode and parks the worker guard for process lifetime so buffered
+/// logs aren't lost. Sibling loggers (hooks/memory/sampling/instrumentation) can
+/// migrate onto this in a follow-up.
+pub(crate) fn non_blocking_file_writer(path: &Path) -> std::io::Result<NonBlocking> {
+    if let Some(parent) = path.parent() {
+        let _ = std::fs::create_dir_all(parent);
+    }
+
+    let file = std::fs::OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(path)?;
+
+    let (non_blocking, guard) = tracing_appender::non_blocking(file);
+    let guards = FILE_LOG_GUARDS.get_or_init(|| Mutex::new(Vec::new()));
+    // Recover from a poisoned mutex so the guard is always parked; dropping it
+    // would shut down the writer thread and silently lose buffered logs.
+    let mut guards = guards
+        .lock()
+        .unwrap_or_else(|poisoned| poisoned.into_inner());
+    guards.push(guard);
+    Ok(non_blocking)
+}
+
+/// Drop all parked worker guards, flushing their non-blocking writers. Call at
+/// process exit so short-lived runs (e.g. headless `grok -p`) don't lose buffered logs.
+pub(crate) fn flush_file_log_guards() {
+    if let Some(m) = FILE_LOG_GUARDS.get() {
+        // Recover from a poisoned mutex so exit-flush still drains the guards.
+        let mut guards = m.lock().unwrap_or_else(|poisoned| poisoned.into_inner());
+        guards.clear(); // dropping each WorkerGuard flushes + joins its writer thread
+    }
+}