feat: default burn-loop model to Gemma 4 with mimo fallback (#799)

Updated 5 burn-loop cron jobs:
- Triage Heartbeat
- PR Review Sweep
- Overnight R&D Loop
- Autonomous Cron Supervisor
- Hermes Philosophy Loop

Fallback chain: Gemma 4 → mimo-v2-pro → qwen3

cron/jobs.json

@@ -26,7 +26,10 @@
       "paused_at": "2026-03-24T16:23:01.614552-04:00",
       "paused_reason": "Dashboard repo frozen - loops redirected to the-nexus",
       "skills": [],
-      "skill": null
+      "skill": null,
+      "model": "google/gemma-4-31b-it",
+      "provider": "openrouter",
+      "fallback_model": "xiaomi/mimo-v2-pro"
     },
     {
       "id": "e29eda4a8548",
@@ -54,7 +57,10 @@
       "paused_at": "2026-03-24T16:23:02.731437-04:00",
       "paused_reason": "Dashboard repo frozen - loops redirected to the-nexus",
       "skills": [],
-      "skill": null
+      "skill": null,
+      "model": "google/gemma-4-31b-it",
+      "provider": "openrouter",
+      "fallback_model": "xiaomi/mimo-v2-pro"
     },
     {
       "id": "a77a87392582",
@@ -108,7 +114,10 @@
       "deliver": "local",
       "origin": null,
       "skills": [],
-      "skill": null
+      "skill": null,
+      "model": "google/gemma-4-31b-it",
+      "provider": "openrouter",
+      "fallback_model": "xiaomi/mimo-v2-pro"
     },
     {
       "id": "muda-audit-weekly",
@@ -195,7 +204,10 @@
       "paused_at": null,
       "paused_reason": null,
       "skills": [],
-      "skill": null
+      "skill": null,
+      "model": "google/gemma-4-31b-it",
+      "provider": "openrouter",
+      "fallback_model": "xiaomi/mimo-v2-pro"
     },
     {
       "id": "tmux-supervisor-513",
@@ -225,7 +237,10 @@
       "skills": [
         "tmux-supervisor"
       ],
-      "skill": "tmux-supervisor"
+      "skill": "tmux-supervisor",
+      "model": "google/gemma-4-31b-it",
+      "provider": "openrouter",
+      "fallback_model": "xiaomi/mimo-v2-pro"
     }
   ],
   "updated_at": "2026-04-13T02:00:00+00:00"