Fix settings toggle overflow + hotkey capture, add theme picker (v0.1.12)

[archdex-art]

Fixes

• Toggle switch thumb overflowed its track. Toggle's knob <span> had no left anchor, so the browser's static-position fallback rendered it flush against — and partly outside — the track's right edge when checked. Added left-0 so translate-x-[3px]/translate-x-[19px] are relative to a known origin. Verified via getBoundingClientRect: thumb now sits a consistent 3px inset on both states.

• Global hotkey capture never saw keystrokes. The bound toggle shortcut stays registered as an OS-level global hotkey the entire time the settings window is open. Pressing that combo (or anything already intercepted) while recording a new one never reached the capture keydown listener — the OS grabbed it first, so "Listening…" looked permanently stuck. Added suspend_toggle_shortcut/resume_toggle_shortcut Tauri commands; the settings window suspends the active hotkey for the duration of a capture session and re-arms it on cancel/failure/unmount (a successful capture re-registers the new combo instead, via the existing update_settings → rebind_toggle path).

Added

• Base theme selector. Appearance now has a Dark/Light theme picker alongside the existing Accent Color swatches, independent of it. New ink/canvas Tailwind colors backed by CSS variables (--ink-rgb, --canvas-rgb) replace every hardcoded white/* / hsl(32,14%,7%) token across the settings window; theme.ts:applyTheme() flips them via a data-theme attribute, so switching themes repaints the whole window live, no reload.

Verification

• tsc --noEmit clean, cargo check clean.
• Drove the settings UI against the Vite dev server in a real browser: confirmed toggle thumb geometry pre/post fix via getBoundingClientRect, confirmed keystroke capture round-trips correctly, and screenshotted General/Appearance/Extensions in both themes for full contrast/legibility.
• Bumped src-tauri/tauri.conf.json + Cargo.toml to 0.1.12, added CHANGELOG entry.