Add NVIDIA NIM platform (provider 11)

The 14th registry row: id "nvidia", NVIDIA_API_KEY > auth.json "nvidia"
scope, https://integrate.api.nvidia.com/v1 with KIGI_NVIDIA_BASE_URL
override, Bearer, ChatCompletions, enrichment-backed metadata
(models_dev_id nvidia — the quirk matrix's earlier 'absent' claim was
wrong; models.dev has 84 nvidia models), restrict_to_enriched=true (the
NIM listing mixes chat/embedding/rerank/vision/image; keep the 45
tool-calling chat models). Slashed org/model ids
(nvidia/meta/llama-3.3-70b-instruct) round-trip via the first-slash split;
the native id rides the wire.

NIM exposes raw vLLM behavior and stream_options support varies per model
(some strict vLLM backends 4xx on it), so chat_compat=StrictOpenAi strips
stream_options — streaming works across the whole fleet, usage falls back
to estimation. Snapshot reasoning models carry no effort menus, so kigi
sends no reasoning_effort (which an unsupported strict validator would
400 on). Review: no defects. Logged note: a key lacking the org 'Public
API Endpoints' permission passes /models validation but 403s on chat
(user-fixable edge case).

crates/codegen/kigi-tui/src/app/app_view.rs

@@ -6894,7 +6894,7 @@ pub(crate) mod tests {
     #[test]
     fn pending_menu_items_lists_interactive_methods_plus_quit() {
         let items = pending_menu_items(&fresh_user_auth_methods(), None);
-        assert_eq!(items.len(), 14, "13 login rows + Quit, got {items:?}");
+        assert_eq!(items.len(), 15, "14 login rows + Quit, got {items:?}");
         assert!(
             matches!(&items[0], PendingMenuItem::Login { label } if label == "Kimi Code (OAuth)"),
             "row 0 must be the OAuth login, got {:?}",
@@ -6985,7 +6985,14 @@ pub(crate) mod tests {
                 label: "Cerebras (API key)".into(),
             }
         );
-        assert_eq!(items[13], PendingMenuItem::Quit);
+        assert_eq!(
+            items[13],
+            PendingMenuItem::ApiKey {
+                target: PlatformLogin(kigi_shell::models::PlatformId::Nvidia),
+                label: "NVIDIA NIM (API key)".into(),
+            }
+        );
+        assert_eq!(items[14], PendingMenuItem::Quit);
         // The non-interactive methods must never appear as rows.
         let byok = kigi_shell::agent::auth_method::build_auth_methods(
             kigi_shell::agent::auth_method::AuthMethodsBuildInputs {
@@ -6996,7 +7003,7 @@ pub(crate) mod tests {
         );
         assert_eq!(
             pending_menu_items(&byok.methods, None).len(),
-            14,
+            15,
             "xai.api_key / cached_token must not add rows"
         );
     }