feat(py): Add DAP helpers to registry

[huangjeff5]

• Wires Dynamic Action Provider (DAP) into Registry.resolve_action: define_dynamic_action_provider now attaches the DynamicActionProvider to the registered DAP Action, and resolution uses get_action(kind, name). Hand-registered providers that still resolve via run({kind, name}) → Action keep working.
• Adds parse_dap_qualified_name and resolve_action_by_key support for /dynamic-action-provider/:/.

This is to support DAP overall. Next PR: Extends the generate path and options typing (tools: list[str | Tool], etc.) using the updated resolve_action / resolve_tool calls from this PR.

[gemini-code-assist]

Code Review

This pull request introduces support for nested actions exposed by Dynamic Action Providers (DAPs). Key changes include the addition of a utility to parse DAP-qualified names in the format provider:innerKind/innerName, updates to the registry's action resolution logic to handle these qualified keys, and the attachment of DAP instances to actions for easier retrieval. The implementation maintains backward compatibility with the legacy action resolution protocol and includes comprehensive tests for the new functionality. I have no feedback to provide.