Add dependency license compliance checks

[DavidBakerEffendi]

Description

Adds a dependency-license compliance system for Mjolnir, its voice worker, bundled native payloads, embedded fonts, and the pinned Anvil binary. This makes license policy enforceable in CI and ensures official release archives contain the corresponding notices and source references.

Key Changes:

• Add deny-by-default cargo-deny policy, generated cargo-about reports, supplemental native/font notices, and inventory guards.
• Add CI checks for policy compliance, report freshness, and packaged legal files.
• Include Mjolnir and pinned Anvil legal bundles in every release archive.
• Correct project SPDX metadata to GPL-3.0-only and document report regeneration.
• Preserve Anvil v0.22.0's shipped license file while adding its missing canonical LGPL text and exact corresponding-source reference.
• Fix Apple libc::openpty compatibility and ignore only the transient macOS PENDIN state in terminal-restoration assertions.
• Keep explicitly enabled or disabled built-in ACP servers visible without detected credentials, with deterministic regression coverage.

Touch Points:

• .github/workflows/ci.yml
• .github/workflows/release.yml
• Cargo.toml
• voice-worker/Cargo.toml
• README.md
• licenses/
• scripts/generate-supplemental-third-party-notices.mjs
• src/council.rs
• tests/termination_pty.rs

Validation:

• cargo deny --workspace --config licenses/deny.toml --locked check licenses
• cargo-about and supplemental-report freshness checks
• cargo fmt --check
• cargo clippy --all-targets -- -D warnings
• cargo test
• cargo build --release
• Cargo package-content checks
• YAML, JavaScript, and Git diff checks