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/build/kigi-proto-build/src/find_protoc.rs

@@ -0,0 +1,93 @@
+use anyhow::{Context, bail};
+use std::env;
+use std::path::{Path, PathBuf};
+use std::process::Command;
+
+fn check_protoc_good(protoc: &Path) -> anyhow::Result<()> {
+    let output = Command::new(protoc)
+        .arg("--version")
+        .output()
+        .context("Failed to execute protoc")?;
+
+    if !output.status.success() {
+        let stdout = String::from_utf8_lossy(&output.stdout);
+        let stderr = String::from_utf8_lossy(&output.stderr);
+        bail!(
+            "protoc --version failed, likely dotslash is missing; \
+             try `cargo install dotslash`; stdout: {stdout:?}, stderr: {stderr:?}"
+        );
+    }
+    Ok(())
+}
+
+fn is_github_actions() -> bool {
+    env::var_os("GITHUB_ACTIONS").is_some()
+}
+
+/// Find `protoc` command.
+///
+/// Search order:
+/// 1. `$PROTOC` environment variable (set by Bazel `build_script_env` or user override)
+/// 2. `bin/protoc` walking up parent directories (dotslash wrapper for local dev)
+/// 3. `protoc` on `$PATH` (system install or other tooling)
+///
+/// When `bin/protoc` exists but fails to execute (e.g. the dotslash wrapper running
+/// in Bazel remote execution where `dotslash` is not installed), the error is not fatal —
+/// we fall through to the PATH-based lookup instead.
+///
+/// Returns `Ok(None)` if not found and not in a strict environment (GitHub Actions).
+pub fn find_protoc() -> anyhow::Result<Option<PathBuf>> {
+    // 1. Check the PROTOC env var first. This is the standard override used by prost-build
+    //    and is set by Bazel cargo_build_script build_script_env to point at a hermetic
+    //    protoc binary instead of the dotslash wrapper.
+    if let Ok(protoc_env) = env::var("PROTOC") {
+        let protoc = PathBuf::from(&protoc_env);
+        if protoc.try_exists()? {
+            check_protoc_good(&protoc)?;
+            return Ok(Some(protoc));
+        }
+    }
+
+    // 2. Walk up directories looking for bin/protoc (dotslash wrapper).
+    let cwd = env::current_dir()?;
+    let mut dir = cwd.clone();
+    let mut dir_rel = PathBuf::new();
+    loop {
+        // Return relative path to make build more deterministic.
+        let protoc = dir_rel.join("bin/protoc");
+        if protoc.try_exists()? {
+            match check_protoc_good(&protoc) {
+                Ok(()) => return Ok(Some(protoc)),
+                Err(e) => {
+                    // bin/protoc exists but can't execute — likely the dotslash wrapper
+                    // in an environment without dotslash (e.g. Bazel remote execution).
+                    // Fall through to PATH-based lookup below.
+                    eprintln!(
+                        "bin/protoc found at `{}` but failed to execute: {e:#}; \
+                         trying protoc from PATH as fallback",
+                        protoc.display()
+                    );
+                    break;
+                }
+            }
+        }
+        if !dir.pop() {
+            break;
+        }
+        dir_rel.push("..");
+    }
+
+    // 3. Try protoc from PATH (system install or other tooling).
+    if check_protoc_good(Path::new("protoc")).is_ok() {
+        return Ok(Some(PathBuf::from("protoc")));
+    }
+
+    // 4. Not found anywhere.
+    if is_github_actions() {
+        return Err(anyhow::anyhow!(
+            "`protoc` not found (checked $PROTOC env, bin/protoc, and PATH)"
+        ));
+    }
+    eprintln!("`protoc` not found; likely it is missing in docker image");
+    Ok(None)
+}