[kiro-support] Add Kiro Support power (Agent Plugins format)

[kirankumar15]

Summary

Add the kiro-support power using the Agent Plugins v1.0.0 specification format. This is the same power as #189 but migrated from the legacy POWER.md format to the portable agent-plugins standard (plugin.json + skills/ + mcp.json).

What this power does

File and manage AWS Support cases for Kiro issues directly from the IDE. Collects diagnostics and verifies Support API access with a read-only probe before any write, and never files, replies to, or resolves a case without explicit user approval.

Backends: awslabs.aws-support-mcp-server (primary) and mcp-proxy-for-aws / Agent Toolkit (fallback, telemetry disabled).

Structure

kiro-support/
├── plugin.json
├── mcp.json
└── skills/
    └── kiro-support/
        ├── SKILL.md
        └── references/
            ├── filing-and-tracking-cases.md
            ├── setup.md
            └── case-safety-and-diagnostics.md

Key differences from #189

• Uses plugin.json manifest instead of POWER.md frontmatter
• mcp.json has $schema and type: stdio per the Agent Plugins spec
• Removed Kiro-specific disabled/autoApprove fields from mcp.json
• Steering files moved to skills/kiro-support/references/
• All content preserved verbatim — only structural migration + improved attachment fallback instructions

Testing

• Installed locally via Kiro Powers UI
• Verified skill activation on keyword match
• Verified reference file loading
• Tested case filing end-to-end with diagnostics auto-capture
• Tested attachment fallback (extract → small file attach)

Related

Supersedes #189