shortcuts and config menu (#4530)

# Description of Changes

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Please provide a summary of the changes, including:

- What was changed
- Why the change was made
- Any challenges encountered

Closes #(issue_number)
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---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

---------

Co-authored-by: Claude <[email protected]>

frontend/src/styles/theme.css

@@ -224,6 +224,15 @@
   --bulk-card-hover-border: #d1d5db; /* slightly darker on hover */
   --unsupported-bar-bg: #5a616e;
   --unsupported-bar-border: #6B7280;
+
+  /* Config Modal colors (light mode) */
+  --modal-nav-bg: #F5F6F8;
+  --modal-nav-section-title: #6B7280;
+  --modal-nav-item: #374151;
+  --modal-nav-item-active: #0A8BFF;
+  --modal-nav-item-active-bg: rgba(10, 139, 255, 0.08);
+  --modal-content-bg: #ffffff;
+  --modal-header-border: rgba(0, 0, 0, 0.06);
 }
 
 [data-mantine-color-scheme="dark"] {
@@ -414,6 +423,15 @@
   --bulk-card-hover-border: var(--border-strong); /* stronger border on hover */
   --unsupported-bar-bg: #1F2329;
   --unsupported-bar-border: #4B525A;
+
+  /* Config Modal colors (dark mode) */
+  --modal-nav-bg: #1F2329;
+  --modal-nav-section-title: #9CA3AF;
+  --modal-nav-item: #D0D6DC;
+  --modal-nav-item-active: #0A8BFF;
+  --modal-nav-item-active-bg: rgba(10, 139, 255, 0.15);
+  --modal-content-bg: #2A2F36;
+  --modal-header-border: rgba(255, 255, 255, 0.08);
 }
 
 /* Dropzone drop state styling */