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/mouse.rs

@@ -698,31 +698,6 @@ impl AgentView {
                             .scrollback
                             .entry_index_at_screen_row(click_row, self.pane_areas.scrollback);
                         if let Some(idx) = hit_idx {
-                            let credit_click = self.scrollback.entry(idx).and_then(|entry| {
-                                if let crate::scrollback::block::RenderBlock::CreditLimit(ref blk) =
-                                    entry.block
-                                {
-                                    Some(blk.url.clone())
-                                } else {
-                                    None
-                                }
-                            });
-                            if let Some(url) = credit_click
-                                && let Some((area, _, _)) = self
-                                    .scrollback
-                                    .entry_screen_area(idx, self.pane_areas.scrollback)
-                            {
-                                let url_row = area.y + area.height.saturating_sub(2);
-                                if click_row >= url_row {
-                                    self.scrollback.set_selected(Some(idx));
-                                    crate::app::link_opener::open_url_if_safe(
-                                        &url,
-                                        crate::terminal::hyperlinks::SchemeFilter::Standard,
-                                    );
-                                    self.last_click = None;
-                                    return InputOutcome::Changed;
-                                }
-                            }
                             let selectable = self
                                 .scrollback
                                 .get(idx)
@@ -878,7 +853,6 @@ impl AgentView {
                     .set_hovered_follow_up_chip(self.follow_up_chip_at(mouse.column, mouse.row));
                 changed |= self.hit_badge.update_hover(mouse.column, mouse.row);
                 changed |= self.hit_context.update_hover(mouse.column, mouse.row);
-                changed |= self.hit_credits.update_hover(mouse.column, mouse.row);
                 changed |= self.hit_todo_close.update_hover(mouse.column, mouse.row);
                 changed |= self.hit_queue_close.update_hover(mouse.column, mouse.row);
                 changed |= self.hit_queue_badge.update_hover(mouse.column, mouse.row);