v0.6.0

What's Changed

• Added drift checks for per-agent hosted tool configurations in capability registries.
• Hosted tool drift diagnostics now report mismatches for the specific agent whose effective config differs from the contract declaration.
• Added validation for hosted_tools.*.agent_configs, including non-empty agent names and string-only config values.
• Added a new CAP090 diagnostic for stale hosted tool agent_configs entries that no longer match any contract declaration.