test: align stale tests with merged Codex preset and bucket changes

CI on main was red because two tests did not follow intentional changes
that were already merged into the codebase:

- codexChatProviderPresets.test.ts still expected the "Kimi For Coding"
  preset, which was removed in 16c3ef3f. Drop the corresponding entry
  from the expected presets map.
- import_export_sync.rs still asserted the legacy per-provider
  model_provider id ("rightcode"), but 9fac15b8 unified Codex
  third-party providers into the stable "custom" history bucket. Mirror
  the assertion update already applied to provider_service.rs.

No production code changed; both fixes only update test expectations.

src-tauri/tests/import_export_sync.rs

@@ -194,8 +194,8 @@ requires_openai_auth = true
 
     assert_eq!(
         parsed.get("model_provider").and_then(|v| v.as_str()),
-        Some("rightcode"),
-        "legacy ConfigService sync should use the stable live provider id"
+        Some("custom"),
+        "legacy ConfigService sync should collapse third-party providers into the stable \"custom\" history bucket"
     );
 
     let model_providers = parsed
@@ -208,7 +208,7 @@ requires_openai_auth = true
     );
     assert_eq!(
         model_providers
-            .get("rightcode")
+            .get("custom")
             .and_then(|v| v.get("base_url"))
             .and_then(|v| v.as_str()),
         Some("https://aihubmix.example/v1")
@@ -221,7 +221,7 @@ requires_openai_auth = true
         .and_then(|v| v.as_str())
         .expect("synced config string");
     assert!(
-        synced_cfg.contains("[model_providers.rightcode]"),
+        synced_cfg.contains("[model_providers.custom]"),
         "ConfigService keeps its existing behavior of syncing provider config from live"
     );
 }

tests/config/codexChatProviderPresets.test.ts

@@ -79,13 +79,6 @@ const expectedChatPresets = new Map<
       contextWindows: { "kimi-k2.6": 262144 },
     },
   ],
-  [
-    "Kimi For Coding",
-    {
-      baseUrl: "https://api.kimi.com/coding/v1",
-      contextWindows: { "kimi-for-coding": 262144 },
-    },
-  ],
   [
     "StepFun",
     {