feat(agents): automatic model fallback when Ollama Cloud is exhausted

Keep ollama-cloud/* as primary. Each agent may declare fallback in
agents.json (xai-oc/grok-*). On quota/auth/provider failure, run-agent
switches once to the fallback and continues retries.

- agents.json: fallback fields for pm/junior/senior/qa/intern
- route.sh: emit fallback to GITHUB_OUTPUT
- agent.yml: pass FALLBACK env into run-agent
- install-opencode.sh: register primary+fallback models in provider maps
- run-agent.sh: failover on quota/credit/429/capacity-class errors

.gitea/workflows/scripts/agents.json

@@ -1,28 +1,31 @@
 {
   "pm": {
-    "model": "xai-oc/grok-4.5",
+    "model": "ollama-cloud/minimax-m3:cloud",
+    "fallback": "xai-oc/grok-4.5",
     "vision": true,
     "mode": "comment",
     "skills": [
       "gitea-api"
     ],
-    "desc": "Product manager & orchestrator — plans and picks the dev, hands each finished PR to @qa for review, and reports back to the issue creator (in autopilot it merges approved PRs itself). Works from the issue thread only — comments only, never edits files, never reads the PR diff. Model: grok-4.5 via xAI (Ollama Cloud quota exhausted)."
+    "desc": "Product manager & orchestrator — plans and picks the dev, hands each finished PR to @qa for review, and reports back to the issue creator (in autopilot it merges approved PRs itself). Works from the issue thread only — comments only, never edits files, never reads the PR diff. Falls back to xAI grok-4.5 if Ollama Cloud is unavailable/quota-exhausted."
   },
   "junior": {
-    "model": "xai-oc/grok-4.3",
+    "model": "ollama-cloud/kimi-k2.7-code:cloud",
+    "fallback": "xai-oc/grok-4.3",
     "vision": false,
     "mode": "pr",
     "skills": [],
-    "desc": "Junior dev — small, low-risk changes (mostly YAML/compose/config). Text-only, cannot read images. Defers complex or image tasks to @senior or @lead. Model: grok-4.3 via xAI."
+    "desc": "Junior dev — small, low-risk changes (mostly YAML/compose/config). Text-only, cannot read images. Defers complex or image tasks to @senior or @lead. Falls back to xAI grok-4.3 if Ollama Cloud fails."
   },
   "senior": {
-    "model": "xai-oc/grok-4.5",
+    "model": "ollama-cloud/glm-5.2:cloud",
+    "fallback": "xai-oc/grok-4.5",
     "vision": false,
     "mode": "pr",
     "skills": [
       "gitea-api"
     ],
-    "desc": "Senior dev — complex, multi-file implementation (text-only). Model: grok-4.5 via xAI (moved off Ollama Cloud)."
+    "desc": "Senior dev — complex, multi-file implementation (GLM-5.2 via Ollama Cloud, text-only). Falls back to xAI grok-4.5 if Ollama Cloud fails."
   },
   "lead": {
     "model": "xai-oc/grok-4.5",
@@ -34,13 +37,14 @@
     "desc": "Tech lead — the hardest problems, architecture, and final calls."
   },
   "qa": {
-    "model": "xai-oc/grok-4.5",
+    "model": "ollama-cloud/minimax-m3:cloud",
+    "fallback": "xai-oc/grok-4.5",
     "vision": true,
     "mode": "comment",
     "skills": [
       "gitea-api"
     ],
-    "desc": "QA / reviewer — reviews PRs: reads the diff, drives a headless browser (Playwright) to verify behavior, posts specific recommendations on the PR and the pass/fail verdict on the issue. Never edits code, never merges. Model: grok-4.5 via xAI."
+    "desc": "QA / reviewer — reviews PRs: reads the diff, drives a headless browser (Playwright) to verify behavior, posts specific recommendations on the PR and the pass/fail verdict on the issue. Never edits code, never merges. Falls back to xAI grok-4.5 if Ollama Cloud fails."
   },
   "ops": {
     "model": "xai-oc/grok-4.5",
@@ -53,9 +57,10 @@
   },
   "intern": {
     "model": "ollama/ornith:35b",
+    "fallback": "xai-oc/grok-4.3",
     "vision": false,
     "mode": "pr",
     "skills": [],
-    "desc": "Intern — very basic tasks only, routed to the local Ollama model (ornith:35b). Text-only, cannot read images. Escalates anything non-trivial to @junior, @senior or @lead."
+    "desc": "Intern — very basic tasks only, routed to the local Ollama model (ornith:35b). Text-only, cannot read images. Escalates anything non-trivial to @junior, @senior or @lead. Falls back to xAI grok-4.3 if local Ollama is down."
   }
 }