Introduce intent-based colors, remove colors.ts

[opyh]

• Removes hard-coded CSS color values where possible and points to the according Radix variables (fixing dark/bright mode)
• introduces reusable CSS color aliases that you can use to signalize an intent in the UI (danger, warning, success)
• tries to use CSS color variables instead of JS-based color where possible. This means, for example, that map marker colors are derived from the CSS.

Further reading:

• Radix UI docs on color aliasing
• Radix UI docs on composing a palette

On the way I've dared a mini refactoring to fix the totally-broken looking mapping events list UI. I hope that's okay :)

IMO the UI changes are only subtle and we'll have another round of polishing, so from my perspective, reviewing just the code would be enough here.

📎 Related Ticket

This code is based on #490. It needs rebasing onto feature/a11ymap before merging.

💪 I have tested my code

- [x] The feature deployment works. - [x] The automated tests are passing. - [x] I have manually tested this feature - [x] in Chrome - [ ] in Firefox - [ ] in Safari

🧼 I have cleaned up my code

- [x] I have removed dependencies that were just for testing. - [x] I have removed debug logging. - [x] My code does not generate new warnings. - [x] My code does not depend on new vulnerable packages. - [x] The commit messages are precise and make sense (rebase the PR with `--interactive` if applicable, keeping commits in sensible chunks if possible).

🔍 I have performed a self-review of my code

- [x] My code is self-documenting or has links to necessary documentation. - [x] New function and variables names can be understood by new developers with basic project knowledge. - [x] The feature fits the design.

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