feat(ui): improve dark mode contrast for editorial readability

[HugoPBrito]

Context

Dark mode on master uses near-black surfaces (zinc-950, stone-950) and dim borders (zinc-800/900) that flatten cards, tables, and inputs into the canvas. This PR tightens dark-theme contrast so elements read clearly without touching light mode, brand colours, or any component code.

Description

Token-only changes scoped to .dark in ui/styles/globals.css and the HeroUI dark theme in ui/tailwind.config.js:

• Canvas anchored to pure black (#000000) with pure-white primary text (#ffffff); secondary text bumped to zinc-200 for readability on the new canvas
• Neutral border scale bumped one tier brighter (zinc-700 / zinc-800) so cards, dividers, and table grids are visible on the new canvas; border-data-emphasis opacity raised from 0.1 to 0.14
• Inputs use a near-black surface (#111111) framed by visible zinc-700 borders, with zinc-500 on press/focus for a clear active state
• Brighter accent text in dark (red-400, orange-400) keeps error / warning states readable on #000
• HeroUI dark background synced to #000000 and foreground to #ffffff so HeroUI components match the CSS tokens

Light mode and brand colours (mint primary, focus, pass / success greens) are untouched. Diff is 19 lines added, 15 modified across two files; no component, type, or behaviour changes.

Steps to review

1. cd ui && pnpm install && pnpm run dev
2. Sign in and toggle theme to Dark from the header
3. Navigate Findings, Compliance, Providers, Scans — confirm: black canvas, defined card / table borders, readable secondary text, clear input boundaries
4. Toggle to Light — confirm visual parity with master

Checklist

Community Checklist

• This feature/issue is listed in here or roadmap.prowler.com
• Is it assigned to me, if not, request it via the issue/feature in here or Prowler Community Slack

• Are there new checks included in this PR? No
• Review if the code is being covered by tests. (token-only change; visual regression covered by manual review)
• Review if code is being documented following https://github.com/google/styleguide/blob/gh-pages/pyguide.md#38-comments-and-docstrings
• Review if backport is needed.
• Review if is needed to change the Readme.md
• Ensure new entries are added to CHANGELOG.md, if applicable.

UI

• All issue/task requirements work as expected on the UI
• Screenshots/Video - Mobile (X < 640px)
• Screenshots/Video - Tablet (640px > X < 1024px)
• Screenshots/Video - Desktop (X > 1024px)
• Ensure new entries are added to ui/CHANGELOG.md

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

✅ Conflict Markers Resolved

All conflict markers have been successfully resolved in this pull request.

[alejandrobailo]

This is something that has to be designed by Brad, and later discussed. Impacting all designs in Figma.
Don't merge this PR @HugoPBrito, let's talk about this soon.

[HugoPBrito]

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