feat: add Crimson White theme

[Hungerdream]

A clean white background theme with red accent colors, inspired by the tomato color palette of Pomodoro.

• Focus round: deep crimson red (#c0392b)

• Short break: soft rose (#f28b82)

• Long break: warm red (#e05252)

• Background: pure white with light gray layers

• Accent: dark red (#a31515)

• Added static/themes/crimson-white.json

• Registered theme in src-tauri/src/themes/mod.rs

• Updated bundled theme count assertion (37 → 38)

• Added dedicated test crimson_white_theme_is_bundled

[Splode]

Thanks for the contribution! The theme itself looks great — all required color keys are present and the palette is clean.

One request before merging: the mod.rs diff includes a number of unrelated changes — removed section comment banners, removed inline doc comments, and several multi-line blocks reformatted onto single lines. These make the diff harder to review and mix unrelated cleanup into a theme PR.

Could you revert src-tauri/src/themes/mod.rs to its original formatting, keeping only the three changes needed to add the theme?

1. The include_str!("../../../static/themes/crimson-white.json") line in BUNDLED_JSON
2. The count assertion bumped from 37 to 38
3. The new crimson_white_theme_is_bundled test

The theme file itself is ready to go — just needs the tidy-up on mod.rs.

[Hungerdream]

Hi @Splode, I've updated the PR as requested. The mod.rs now contains only the 3 minimal changes needed to add the Crimson White theme. Ready for review!

[Splode]

@Hungerdream Looks good, thank you!