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/performance-engineer.md

@@ -1,7 +1,7 @@
 ---
 description: Reviews code for performance issues. Focuses on efficiency, N+1 queries, memory leaks, and algorithmic complexity (GNS-2 Tier 0)
 mode: all
-model: ollama-cloud/minimax-m3
+model: ollama-cloud/nemotron-3-super
 variant: thinking
 color: "#0D9488"
 permission: