Fix color regressions, add priority color (#37417) (#37421)

Backport #37417 by @silverwind

- fix markup attention block regressions on 2 colors
- added new color "priority" color for important severity in markup
- all message-box style, and error form elements use monochrome text
- tweaked and improved action logs colors

<img width="722" height="637" alt="Screenshot 2026-04-25 at 17 02 49"
src="https://github.com/user-attachments/assets/e8316fd8-3889-4f67-bdc5-39429b5a7eef"
/>
<img width="885" height="123" alt="image"
src="https://github.com/user-attachments/assets/4a761834-e69a-4f5e-a39d-8e49b75fc39d"
/>

<img width="608" height="554" alt="Screenshot 2026-04-25 at 17 03 16"
src="https://github.com/user-attachments/assets/86694726-817a-42b9-91dc-005bc03720cd"
/>

<img width="319" height="279" alt="image"
src="https://github.com/user-attachments/assets/db2801e9-8963-448c-b1b8-3029a69d5cf3"
/>

<img width="396" height="345" alt="image"
src="https://github.com/user-attachments/assets/8195c20d-e034-442c-b0db-4a8455792d0c"
/>


Fixes: #37416

---
This PR was written with the help of Claude Opus 4.7

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>

web_src/css/admin.css

@@ -55,5 +55,5 @@
   padding: 1em 1.5em;
   border: 1px solid var(--color-info-border);
   background: var(--color-info-bg);
-  color: var(--color-info-text);
+  color: var(--color-text);
 }