chore(agents): sync agent configs — model updates to nemotron-3-super

- Update agent model assignments (nemotron-3-ultra -> nemotron-3-super) across .kilo/agents, kilo-meta.json, kilo.jsonc, capability-index.yaml
- Sync agent descriptions in KILO_SPEC.md

.kilo/agents/flutter-developer.md

@@ -1,7 +1,7 @@
 ---
 description: Flutter mobile specialist for cross-platform apps, state management, and UI components
 mode: all
-model: ollama-cloud/qwen3.5:397b
+model: ollama-cloud/deepseek-v4-flash:0731
 variant: thinking
 color: "#02569B"
 permission: