[task] Document string-to-number coercion in schema descriptions

[github-actions]

Objective

Update JSON schema field descriptions to document that numeric fields accept string representations for YAML compatibility.

Context

Related to discussion #4307. The runtime accepts string representations of numbers (e.g., timeout: "300") and automatically converts them using strconv.Atoi(), but the schema only defines "type": "integer". This creates validation gaps where workflows work at runtime but fail external schema validation.

Approach

1. Update schema descriptions in pkg/parser/schemas/main_workflow_schema.json for affected fields
2. Add explicit documentation that strings are accepted and converted
3. Add examples showing both numeric and string formats
4. Consider adding $comment fields for tooling authors

Affected Fields

• timeout-minutes: Currently "type": "integer", accepts string
• max: Currently "type": "integer", accepts string
• max-turns: Currently "type": "integer", accepts string
• max-patch-size: Currently "type": "integer", accepts string

Files to Modify

• Update: pkg/parser/schemas/main_workflow_schema.json (add descriptions to field definitions)

Acceptance Criteria

• Schema descriptions explicitly mention string-to-number coercion
• Examples show both formats: timeout: 300 and timeout: "300"
• $comment fields added explaining conversion rules for tooling authors
• Documentation clearly states: "Accepts numeric values as strings (e.g., '300') for YAML compatibility"

Implementation Notes

Code Evidence from pkg/workflow/metrics.go:245-257:

func ConvertToInt(val any) int {
    switch v := val.(type) {
    case int:
        return v
    case int64:
        return int(v)
    case float64:
        return int(v)
    case string:  // This behavior needs documentation
        if i, err := strconv.Atoi(v); err == nil {
            return i
        }
    }
    return 0
}

AI generated by Plan Command for discussion #4307