Bump AWF container images to v0.25.40

[lpcox]

Request

Bump the default AWF container image versions from the current pinned version to v0.25.40.

Images to update

• ghcr.io/github/gh-aw-firewall/agent:0.25.29 → 0.25.40
• ghcr.io/github/gh-aw-firewall/squid:0.25.29 → 0.25.40
• ghcr.io/github/gh-aw-firewall/api-proxy:0.25.29 → 0.25.40

Context

The gh-aw-firewall repo has released v0.25.40 with several fixes and improvements. Workflows compiled with gh-aw currently pin to v0.25.29 containers. This update will ensure new compilations use the latest container images.

Expected change

Update the default container version in the gh-aw compiler/manifest so that gh aw compile produces lock files referencing 0.25.40 images.