Refine dark theme and unify controls

[SHAREN]

Summary

• Move the dark theme to a calmer graphite palette with shared surface, text, and semantic tokens
• Replace the native sort select with a custom dark dropdown so the menu no longer opens with a white system style
• Unify account cards, progress bars, modals, toasts, and updater controls around consistent primary, secondary, warning, and destructive roles
• Switch the npm tauri script to call the local Tauri CLI directly and sync the Cargo lockfile package version

Testing

• corepack pnpm build
• corepack pnpm tauri build --no-bundle

[Lampese]

Requesting changes for two regressions introduced alongside the visual refresh:

1. The pnpm tauri script change drops the existing wrapper that bootstraps the Rust toolchain environment. The current scripts/tauri.sh script sources ~/.cargo/env when cargo is not already on PATH and gives a clearer failure path for common rustup-based setups. Replacing it with a direct tauri invocation can break existing developer environments that currently work with pnpm tauri ....

2. The custom sort dropdown replaces the native <select> with a button + listbox implementation, but it does not restore the keyboard semantics that the native control provided. There is no arrow-key navigation, no active-descendant/focus management for options, and no typeahead behavior. That makes this a real accessibility regression rather than just a visual restyle.

I think both issues should be resolved before merging. The theme work itself looks coherent, but these two changes broaden the PR from a visual polish pass into behavior regressions for both developers and keyboard users.