connector-v0.1.0

Add local signing connector (radixdlt-connector-mcp) + SDK polish

New crate `radixdlt-connector-mcp`: a local MCP server (stdio) that pairs a
Radix Wallet over Radix Connect and gets transactions signed on the user's
machine — pairing QR (unicode + PNG), send_transaction, pre-authorization,
ROLA account proof and transaction status. Backed by radixdlt-connect.

Distribution is GitHub-only (no crates.io/npm): install scripts for
Linux/macOS (install-connector.sh) and Windows (install-connector.ps1), a
release workflow that cross-builds Linux/macOS/Windows binaries, and a CI job.

Also includes earlier SDK polish:
- i18n: `Lang` is #[non_exhaustive] and `tr!` gains labelled arms with an
  English fallback, so adding a language is non-breaking.
- connect-iroh: `Relay` enum replaces the bool flag in `bind_with`.
- connect: shared interactionId response correlation across all signing calls;
  multi-device `LinkState` documented in the README.
- Doc-link, clippy and fmt fixes across the workspace.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>