chore: prepare gmutils v0.8.0-beta.3

[eareimu]

Summary

Prepare gmutils v0.8.0-beta.3 preview release.

Release surfaces

• Product/package release: gmutils v0.8.0-beta.3 preview channel
• crates.io workspace members: genmeta, genmeta-curl, genmeta-ssh, genmeta-access, genmeta-identity, genmeta-proxy, genmeta-discover, genmeta-doctor, genmeta-nat, genmeta-nslookup
• Package managers: DEB/RPM, Homebrew preview, Scoop preview
• planned tag: v0.8.0-beta.3

Changes

• Consume access-control APIs through the dhttp facade.
• Add explicit DHTTP identity shorthand support to access-rule flows.
• Keep CLI progress integration opt-in.
• Update release workflows to upload package assets from publish reports.
• Make genmeta discover mDNS suffix test independent of release mDNS service configuration.

Verification

Previously run locally with temporary same-wave upstream patches:

• cargo +nightly fmt -- --check
• cargo test
• cargo clippy --all-targets --all-features -- -D warnings

Registry/package gates

• Requires same-wave upstream crates visible on crates.io before final lockfile convergence and merge/tag.
• Requires genmeta-xtask-release v0.2.0-beta.8 tag for release tooling.
• Scoop preview has an older open gmutils PR that must be merged/closed/superseded before final Scoop publication.