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-mermaid/Cargo.toml

@@ -0,0 +1,36 @@
+[package]
+license = "Apache-2.0"
+name = "kigi-mermaid"
+version.workspace = true
+edition.workspace = true
+description = "Render Mermaid diagram source to a rasterized PNG behind a swappable engine trait"
+
+[dependencies]
+# SVG -> PNG rasterization. `resvg` re-exports the matching `usvg` (0.47) and
+# `tiny_skia`; we deliberately use `resvg::usvg` rather than the workspace
+# `usvg` (0.45.1) so `resvg::render` typechecks against the tree we parse.
+resvg = { workspace = true }
+tiny-skia = { workspace = true }
+fontdb = { workspace = true }
+thiserror = { workspace = true }
+tracing = { workspace = true }
+which = { workspace = true }
+# Subprocess infra (MmdcEngine + the out-of-process render child): detached
+# spawning + wall-clock timeout + process-group reaping.
+kigi-tty-utils = { workspace = true }
+wait-timeout = { workspace = true }
+tempfile = { workspace = true }
+# Vendored dagre-based Mermaid -> SVG engine (third_party/mermaid-to-svg, MIT).
+# Always compiled — the default engine, no feature gate.
+mermaid-to-svg = { workspace = true }
+
+# Subprocess process-group reaping (killpg) for the sync subprocess path, since
+# kigi-tty-utils' ProcessGroup only wraps tokio children.
+[target.'cfg(unix)'.dependencies]
+libc = { workspace = true }
+
+[dev-dependencies]
+# `png` codec enabled LOCALLY only (workspace pins image with
+# default-features=false; "Do not add features globally"). Used by tests to
+# decode the output PNG and assert its dimensions.
+image = { workspace = true, features = ["png"] }