AP-034: restore Auths Rust package coordinates

[bordumb]

Scope

Implements AP34-PR2 on top of #55. Adds a thin, no-I/O auths core facade over the bounded auths-proof component, restores the primary SDK package name to auths-sdk, updates the Cargo graph and lockfile, and reconciles architecture/compliance/semantic-freeze inventories to the expected 28-crate public closure.

Tests and evidence

• No local checks were run, per AGENTS.md. GitHub Actions is the sole verification run.
• The new facade contains a compile-checked rustdoc consumer example in hosted CI.
• Existing authoritative CI owns all-features/no-default-features, package metadata, architecture graph, compliance, documentation, and semantic-freeze drift checks.
• Semantic-freeze owner digests were regenerated from the exact changed owner files; hosted CI remains authoritative.

Affected claims

• auths is the supported consumer-facing Rust core facade.
• auths-proof remains the bounded proof-protocol component.
• auths-sdk is the supported Rust SDK coordinate.
• The first-RC Rust roots are auths and auths-sdk; their expected publishable normal-dependency closure is 28 packages.
• The core facade adds no provider, profile, custody, transport, or stateful runtime behavior.

Exclusions

This PR does not rename npm or Python packages, update the RC tag/artifact identity, add stale-name enforcement, publish or yank packages, create a tag, change package ownership, rename/archive a repository, deploy a site, or change DNS.

Remaining gates

• AP-034: govern the Auths public naming migration #55 must merge before this stacked PR can retarget main.
• Hosted CI must pass before any code merge.
• AP34-PR3 language SDK/current-doc migration.
• AP34-PR4 release identity and stale-name enforcement.
• AP34-PR5 predecessor notice/ledger.
• AP34-PR6 auths.dev content alignment.
• Separate exact-manifest authorization before any publication or RC tag.