feat: define structured issue triage output

.github/ai/triage-schema.json

@@ -0,0 +1,66 @@
+{
+  "type": "object",
+  "additionalProperties": false,
+  "properties": {
+    "category": {
+      "type": "string",
+      "enum": [
+        "question",
+        "missing_information",
+        "bug",
+        "improvement",
+        "new_addon_request",
+        "unsupported",
+        "spam"
+      ]
+    },
+    "confidence": {
+      "type": "number",
+      "minimum": 0,
+      "maximum": 1
+    },
+    "addon": {
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "needs_repository_analysis": {
+      "type": "boolean"
+    },
+    "safe_to_answer_automatically": {
+      "type": "boolean"
+    },
+    "risk": {
+      "type": "string",
+      "enum": [
+        "low",
+        "medium",
+        "high"
+      ]
+    },
+    "summary": {
+      "type": "string"
+    },
+    "response": {
+      "type": "string"
+    },
+    "missing_information": {
+      "type": "array",
+      "items": {
+        "type": "string"
+      }
+    }
+  },
+  "required": [
+    "category",
+    "confidence",
+    "addon",
+    "needs_repository_analysis",
+    "safe_to_answer_automatically",
+    "risk",
+    "summary",
+    "response",
+    "missing_information"
+  ]
+}