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/app/dispatch/settings/ui.rs

@@ -44,7 +44,6 @@ pub(crate) fn refresh_open_settings_modals(app: &mut AppView) {
     }
     let ui_snapshot = app.current_ui.clone();
     // Capture app-level fields before the mut-borrow loop.
-    let coding_data_sharing_opt_out_from_app = app.coding_data_retention_opt_out;
     let show_tips_from_app = app.show_tips;
     let auto_update_from_app = app.auto_update;
     let respect_manual_folds_from_app = app.appearance.scrollback.scroll.respect_manual_folds;
@@ -76,7 +75,6 @@ pub(crate) fn refresh_open_settings_modals(app: &mut AppView) {
                     .iter()
                     .map(|(id, info)| (info.name.clone(), id.clone()))
                     .collect(),
-                coding_data_sharing_opt_out: coding_data_sharing_opt_out_from_app,
                 // Prefer optimistic pending over confirmed active.
                 plan_mode_active: agent.plan_mode_pending.unwrap_or(agent.plan_mode_active),
                 show_tips: show_tips_from_app,
@@ -110,7 +108,7 @@ pub(in crate::app::dispatch) fn dispatch_open_command_palette(app: &mut AppView)
         return vec![];
     }
     agent.active_modal = Some(ActiveModal::CommandPalette {
-        entries: crate::views::modal::default_palette_entries(agent.sharing_enabled),
+        entries: crate::views::modal::default_palette_entries(),
         // Type-to-find: open in input mode (matches Ctrl+P).
         state: crate::views::picker::PickerState::input_active(),
         window: crate::views::modal_window::ModalWindowState::new(),
@@ -149,7 +147,6 @@ pub(in crate::app::dispatch) fn dispatch_open_settings(app: &mut AppView) -> Vec
     let registry = app.settings_registry.clone();
     let ui_snapshot = app.current_ui.clone();
     // Capture app-level fields before the mut-borrow on the agent.
-    let coding_data_sharing_opt_out_from_app = app.coding_data_retention_opt_out;
     let show_tips_from_app = app.show_tips;
     let auto_update_from_app = app.auto_update;
     let respect_manual_folds_from_app = app.appearance.scrollback.scroll.respect_manual_folds;
@@ -187,7 +184,6 @@ pub(in crate::app::dispatch) fn dispatch_open_settings(app: &mut AppView) -> Vec
             .iter()
             .map(|(id, info)| (info.name.clone(), id.clone()))
             .collect(),
-        coding_data_sharing_opt_out: coding_data_sharing_opt_out_from_app,
         // Prefer optimistic pending over confirmed active.
         plan_mode_active: agent.plan_mode_pending.unwrap_or(agent.plan_mode_active),
         show_tips: show_tips_from_app,
@@ -657,7 +653,6 @@ pub(crate) fn build_pager_snapshot(app: &AppView) -> crate::settings::PagerLocal
         auto_mode: agent_auto_mode(app),
         current_model_name: agent_current_model_name(app),
         available_models: agent_available_models(app),
-        coding_data_sharing_opt_out: app.coding_data_retention_opt_out,
         plan_mode_active: agent_plan_mode(app),
         show_tips: app.show_tips,
         auto_update: app.auto_update,
@@ -793,14 +788,6 @@ pub(in crate::app::dispatch) fn action_for_reset(
         }
         // max_thoughts_width: direct round-trip.
         ("max_thoughts_width", SettingValue::Int(i)) => Some(Action::SetMaxThoughtsWidth(*i)),
-        // coding_data_sharing: "opt-in" / "opt-out" → bool.
-        // "opt-out" arm is a skew guard (default is "opt-in").
-        ("coding_data_sharing", SettingValue::Enum("opt-in")) => {
-            Some(Action::SetCodingDataSharing { opted_in: true })
-        }
-        ("coding_data_sharing", SettingValue::Enum("opt-out")) => {
-            Some(Action::SetCodingDataSharing { opted_in: false })
-        }
         // plan_mode: "on" / "off" → PlanModeKind.
         // "on" arm is a skew guard (default is "off").
         ("plan_mode", SettingValue::Enum("off")) => {