Add confidence intent support to issue-mutating safe outputs

[Copilot]

This change adds optional confidence support (0–100) to issue-mutating safe outputs so intent certainty can be carried through issue updates, type assignment, and field updates. It aligns safe-output contracts with newer MCP issue mutation semantics while preserving compatibility with backends that do not yet accept confidence.

• Schema and contract updates

  • Added confidence to tool schemas for:
    • update_issue
    • set_issue_type
    • set_issue_field
  • Added range constraints (minimum: 0, maximum: 100) and tightened prompt guidance on when to provide confidence.
  • Updated shared TypeScript safe-output types to include optional confidence.

• Runtime propagation

  • Plumbed confidence through handler payload construction for the three issue-mutation paths.
  • For GraphQL issue field updates, confidence is attached at the field input level.
  • Handler result/preview payloads now surface confidence where provided.

• Validation model enhancements

  • Extended validation config/engine to support numeric range checks (minimum/maximum) for number fields.
  • Applied range validation to confidence-bearing issue mutation types.

• Compatibility behavior

  • Added graceful fallback: if a target API rejects confidence, handlers retry without it instead of failing the safe-output operation.

{
  "type": "set_issue_field",
  "issue_number": 123,
  "field_name": "Priority",
  "value": "P1",
  "confidence": 82
}