Release v2.1.1

[userFRM]

Summary

• bump all Rust crates and the npm package from 2.1.0 to 2.1.1
• update internal dependency pins and lockfiles so the release version is fully synchronized
• add a 2.1.1 changelog entry covering the packaging, CI, subscription, and documentation fixes already merged

Verification

• cargo test
• cargo test --manifest-path crates/tauri-plugin-conduit/Cargo.toml
• cd packages/tauri-plugin-conduit && npm test
• cd packages/tauri-plugin-conduit && npm run check
• cd packages/tauri-plugin-conduit && npm run build && npm pack --dry-run 2>&1 | tee /tmp/tauri-plugin-conduit-pack-2.1.1.txt >/dev/null && grep 'dist/index.js' /tmp/tauri-plugin-conduit-pack-2.1.1.txt