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-tui/src/settings/defs.rs

@@ -119,30 +119,6 @@ const PERMISSION_MODE_CHOICES: &[EnumChoice] = &[
     },
 ];
 
-// ---------------------------------------------------------------------------
-// Coding-data-sharing catalog.
-//
-// Persisted in auth metadata (`AuthEntry::coding_data_retention_opt_out`),
-// NOT config.toml. Two choices only — the pager has no `Option`/`Unset`
-// representation for this field.
-//
-// `supports_preview: false` — toggling fires an async ACP call that
-// can fail. Commit on Enter only.
-// ---------------------------------------------------------------------------
-
-const CODING_DATA_SHARING_CHOICES: &[EnumChoice] = &[
-    EnumChoice {
-        canonical: "opt-in",
-        display: "Opt in",
-        description: "Allow SpaceXAI to retain and use coding session data for training and product improvement.",
-    },
-    EnumChoice {
-        canonical: "opt-out",
-        display: "Opt out",
-        description: "Do not retain coding session data. Code requests will not be used for training.",
-    },
-];
-
 // ---------------------------------------------------------------------------
 // Plan-mode catalog.
 //
@@ -947,35 +923,6 @@ pub fn default_settings() -> Vec<SettingMeta> {
             restart_required: false,
             hidden_in_minimal: false,
         },
-        // SHELL-owned. Persisted in auth metadata (not config.toml).
-        // Reads from `PagerLocalSnapshot.coding_data_sharing_opt_out`.
-        // Default "opt-in" matches `AuthEntry::coding_data_retention_opt_out = false`.
-        // ZDR / non-admin guards are enforced at dispatch time.
-        SettingMeta {
-            key: "coding_data_sharing",
-            category: SettingCategory::Privacy,
-            owner: SettingOwner::Shell,
-            label: "Coding data sharing",
-            description: "Controls whether SpaceXAI may retain and train on coding session data.",
-            keywords: &[
-                "privacy",
-                "data",
-                "sharing",
-                "coding",
-                "retention",
-                "telemetry",
-                "training",
-                "opt-in",
-                "opt-out",
-            ],
-            kind: SettingKind::Enum {
-                default: "opt-in",
-                choices: CODING_DATA_SHARING_CHOICES,
-                supports_preview: false,
-            },
-            restart_required: false,
-            hidden_in_minimal: false,
-        },
         // SHELL-owned, persisted to `[ui].default_selected_permission` in
         // config.toml. Read by the pager via `appearance::permission_cursor`.
         // Canonical `always_allow_all_sessions` (the effective default) lands