Remove vulnerable embedded cli-proxy:0.27.43 digest pin

[Copilot]

The shared action pin metadata still embedded a digest for ghcr.io/github/gh-aw-firewall/cli-proxy:0.27.43, which kept a known-vulnerable image resolvable even though the runtime should be able to fall back to the tag. This change removes that embedded digest pin and aligns workflow pinning expectations with the new fallback behavior.

• Pin data

  • Remove the cli-proxy:0.27.43 entry from the shared container pin tables:
    • .github/aw/actions-lock.json
    • pkg/actionpins/data/action_pins.json
    • pkg/workflow/data/action_pins.json
  • Preserve the existing embedded pins for the other AWF sidecars (agent, api-proxy, squid).

• Compiler behavior contract

  • Keep cli-proxy usable via its tagged image reference when no embedded digest pin exists.
  • Continue emitting digest metadata only for sidecars that still have trusted embedded pins.

• Regression coverage

  • Update focused workflow pinning tests to assert:
    • agent, api-proxy, and squid remain digest-pinned by default
    • cli-proxy falls back to ghcr.io/github/gh-aw-firewall/cli-proxy:<tag>
    • AWF image-tag digest metadata no longer includes cli-proxy=sha256:...

imageTag := strings.TrimPrefix(string(constants.DefaultFirewallVersion), "v")
image := constants.DefaultFirewallRegistry + "/cli-proxy:" + imageTag

refs, pinEntries := applyContainerPins([]string{image}, nil)

// No embedded digest pin: keep the tag reference.
assert.Equal(t, image, refs[0])
assert.Empty(t, pinEntries[0].Digest)

• Fixes [container-image-scan] Container findings for ghcr.io/github/gh-aw-firewall/cli-proxy:0.27.43 #49506