Upgrade gh-aw-mcpg to v0.4.10

[lpcox]

Summary

Upgrade the MCP Gateway image from ghcr.io/github/gh-aw-mcpg:v0.4.9 to v0.4.10.

Scope

• Update the canonical MCP Gateway version and immutable image digest used by the compiler.
• Update generated actions metadata and fixtures that pin v0.4.9.
• Recompile repository workflows so manifests, image download steps, MCP_GATEWAY_DOCKER_COMMAND, and CLI proxy references consistently use v0.4.10.
• Update documentation or tests that explicitly reference v0.4.9.
• Confirm no stale v0.4.9 image references remain.

Motivation

v0.4.10 includes GitHub guard coverage improvements, DIFC/guard hardening and diagnostics, remote schema $ref support, tracing updates, and workflow compatibility updates since v0.4.9.

Acceptance criteria

• Compiler-generated workflows use v0.4.10 with the published immutable digest.
• Generated fixtures and workflow lock files are synchronized.
• Relevant compiler, MCP Gateway, CLI proxy, and workflow compilation tests pass.