M1/F1: Kimi Code OAuth device-code flow

Replace the xAI OAuth stack with the Kimi device authorization grant:
- kimi_oauth.rs wire layer (device_authorization + token poll + refresh
  against kigi_env::oauth_host(); client_id per PRD; retryable statuses
  429/5xx with backoff; expired_token restarts authorization)
- X-Msh-Device-{Name,Model,Id} headers; device_id minted uuid4-hex at
  ~/.kigi/device_id (0600)
- Storage: system keyring service `kigi`, entry `oauth/kimi-code`
  (macOS/Windows native backends), atomic-file fallback under ~/.kigi;
  official client's keyring/~/.kimi never touched
- Refresh manager: 60s tick, threshold max(300, expires_in*0.5),
  401-tombstone keyed by rejected refresh token with 300s cooldown and
  rotation auto-clear, cross-process lock with sibling-adoption
  triple-check, sleep/wake forced refresh
- Deleted xAI machinery: enterprise OIDC (PKCE/JWKS/teams), devbox login,
  external auth provider, JWT tier gating + subscription paywall stack,
  X-XAI-Token-Auth marker headers, ZDR gates, /user enrichment
- kigi login / TUI /login both drive the device flow; login-host display
  now derives from kigi_env::oauth_host()
- 264 auth unit/wiremock tests; live contract probe of
  auth.kimi.com/api/oauth/device_authorization matches the wire shapes

Gates: check/clippy --all-targets clean, fmt, deny ok, kigi-shell lib
5131 tests green.

crates/codegen/kigi-shell/src/extensions/session_admin.rs

@@ -111,10 +111,7 @@ async fn handle_session_rename(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtR
     // Send a SessionSummaryGenerated notification so the TUI updates its title
     notify_session_title(agent, session_id, &req.title).await;
 
-    if agent.is_writeback_storage()
-        && let Some(auth) = agent.current_auth()
-        && !auth.is_zdr_team()
-    {
+    if agent.is_writeback_storage() && agent.current_auth().is_some() {
         use crate::remote::client::BackendClient;
         use crate::session::export::ExportedMetadata;
 
@@ -133,15 +130,7 @@ async fn handle_session_rename(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtR
     // Hook 2: update session replica with summary (fire-and-forget)
     if let Some(client) = agent.session_registry_client() {
         let sid = req.session_id.to_string();
-        let title = if agent
-            .auth_manager
-            .current_or_expired()
-            .is_some_and(|a| a.is_zdr_team())
-        {
-            None
-        } else {
-            Some(req.title.clone())
-        };
+        let title = Some(req.title.clone());
         tokio::spawn(async move {
             let update = crate::agent::session_registry_client::UpdateRequest {
                 summary: title,
@@ -248,8 +237,7 @@ async fn handle_session_delete(agent: &MvpAgent, args: &acp::ExtRequest) -> ExtR
     // For writeback storage (non-ZDR): remote delete is authoritative for
     // the cloud history and runs first; on failure no local bits are
     // touched so the pager does not remove the row or toast success.
-    let needs_remote =
-        agent.is_writeback_storage() && agent.current_auth().is_some_and(|a| !a.is_zdr_team());
+    let needs_remote = agent.is_writeback_storage() && agent.current_auth().is_some();
 
     // Shared delete: remote-first, then local disk + FTS eviction.
     // Mirrored by the `grok sessions delete <id>` CLI path.