F3: Kimi inference pipeline + full grok cloud-surface excision

Sampler / inference (PRD F3):
- kimi_compat.rs: single adaptation point for the Kimi chat/completions
  dialect (thinking-field mapping, model_id stripping, empty-content
  tool-call message fix, stream_options.include_usage), with kimi-cli
  source citations
- Rate-limit handling reworked for Kimi/Moonshot semantics; UA kigi/{version}
- /models replaces the xAI models-v2 endpoint everywhere; idle model
  refresh carries X-Msh-* device headers only (X-XAI-Token-Auth and
  x-grok-client-mode/CLIENT_MODE_HEADER machinery deleted)

Cloud-surface excision (PRD §5, zero-egress):
- remote/ conversations lane, cli-chat-proxy-types crate, prod/ dir,
  share command, credit bar: deleted (single local session lane;
  paginate() replaces merge_and_paginate)
- Subscription/tier gate stack deleted end-to-end: AppView
  gate/tier/team/ZDR fields, app/subscription.rs watch loop,
  dispatch/billing.rs paywall + SuperGrok upsell, free-usage-exhausted
  chain, tier-restricted commands, GateInfo, RemoteSettings gate fields,
  SettingsUpdateNotification gate fields
- /privacy + coding-data-sharing setting deleted (backed by a dead xAI
  RPC; Kigi is zero-egress — nothing to share or retain remotely)

Auth UX correctness (user-reported):
- Device-flow fixtures now mirror the live Kimi payload shape
  (https://www.kimi.com/code/authorize_device?user_code=..., verified
  against auth.kimi.com); the fabricated auth.kimi.com/device?code=...
  URLs are gone
- open_browser_detached is a no-op under cfg(test): unit tests drove
  wiremock fixture URLs into the real browser (root cause of the
  "garbage mock link" ABCD-1234 tabs)
- Welcome/pager-minimal rebrand: Grok Build -> Kigi, grok.com ->
  kimi.com, "Sign in to Grok" -> "Sign in to Kimi"

crates/codegen/kigi-config/src/validation.rs

@@ -7,11 +7,21 @@ use crate::loader::{apply_version_overrides_with_registered, load_toml_file};
 use crate::paths::{system_config_dir, user_kigi_home};
 use crate::version_overrides::{VersionOverrideError, apply_version_overrides};
 
-use prod_mc_cli_chat_proxy_types::FAIL_CLOSED_KEY;
-/// The canonical opt-in key + string parse live in the shared types crate, next to
-/// the signed payload that carries the flag, so the server-side signer and this
-/// client parse the same semantics.
-pub use prod_mc_cli_chat_proxy_types::fail_closed_flag_from_str;
+/// The `requirements.toml` opt-in key for strict (fail-closed) enforcement.
+/// Lives next to the signed payload that carries the flag
+/// ([`crate::signed_policy::SignedPayload::fail_closed`]) so the two sides
+/// can't drift.
+pub const FAIL_CLOSED_KEY: &str = "fail_closed";
+
+/// Read the `fail_closed` opt-in from a requirements-TOML string — THE canonical
+/// parse shared by every caller so the semantics can't drift.
+/// Invalid TOML or a non-bool value → `false`.
+pub fn fail_closed_flag_from_str(requirements: &str) -> bool {
+    toml::from_str::<toml::Value>(requirements)
+        .ok()
+        .and_then(|v| v.get(FAIL_CLOSED_KEY).and_then(toml::Value::as_bool))
+        .unwrap_or(false)
+}
 
 /// Read the `fail_closed` opt-in from a parsed requirements layer — same semantics as
 /// [`fail_closed_flag_from_str`]. Env tightening (file vs `KIGI_MANAGED_CONFIG_FAIL_CLOSED`)