Release Xikoi 0.1.0

[xerexcoded]

What

• adds guided xikoi setup and xikoi doctor flows
• eagerly installs/checks Ollama, selects and pulls the RAM-appropriate Qwen chat model, and prepares the pinned MLX voice runtime
• manages the local voice sidecar during normal launches
• adds dual licensing, crates.io metadata, release documentation, and Apple Silicon release automation

Why

Make Xikoi installable by other users without deferring multi-gigabyte model downloads until the first STT/TTS request.

Impact

Apple Silicon macOS gets the complete local voice experience. Other supported builds retain text chat and best-effort audio support. Setup is explicit and reports its downloads before proceeding.

Checks

• cargo fmt --check
• cargo test --all-features (83 passed; one opt-in Ollama integration test skipped)
• strict Clippy with warnings denied
• cargo audit
• cargo publish --dry-run --locked
• packaged release-mode cargo install smoke test
• nix flake check --print-build-logs
• isolated real setup/doctor warm-up covering Ollama, MLX TTS, MLX ASR, and audio devices