feat(schema): add capabilities field to model schema

Add new required `capabilities` field to model schema to track advanced
model features including function-calling, tool-choice, structured-outputs,
and reasoning capabilities.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: ericyangpan

manifests/$schemas/model.schema.json

@@ -57,6 +57,15 @@
           "uniqueItems": true,
           "minItems": 1
         },
+        "capabilities": {
+          "type": "array",
+          "description": "Advanced capabilities supported by the model",
+          "items": {
+            "type": "string",
+            "enum": ["function-calling", "tool-choice", "structured-outputs", "reasoning"]
+          },
+          "uniqueItems": true
+        },
         "benchmarks": {
           "type": "object",
           "description": "Performance scores from coding and multimodal benchmarks",
@@ -104,6 +113,7 @@
         "tokenPricing",
         "releaseDate",
         "inputModalities",
+        "capabilities",
         "benchmarks",
         "platformUrls"
       ]