Feature/v2/all tools sidebar (#4151)

# Description of Changes

- Added the all tools sidebar
- Added a TextFit component that shrinks text to fit containers
- Added a TopToolIcon on the nav, that animates down to give users
feedback on what tool is selected
- Added the baseToolRegistry, to replace the old pattern of listing
tools, allowing us to clean up the ToolRegistry code
- Fixed Mantine light/dark theme race condition 
- General styling tweaks

---

## 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.

frontend/src/styles/theme.css

@@ -81,7 +81,7 @@
   --text-secondary: #4b5563;
   --text-muted: #6b7280;
   --border-subtle: #e5e7eb;
-  --border-default: #d1d5db;
+  --border-default: #E2E8F0;
   --border-strong: #9ca3af;
   --hover-bg: #f9fafb;
   --active-bg: #f3f4f6;
@@ -117,11 +117,31 @@
   --icon-inactive-bg: #9CA3AF;
   --icon-inactive-color: #FFFFFF;
 
+  /* New theme colors for text and icons */
+  --tools-text-and-icon-color: #374151;
+
+  /* Tool picker sticky header variables (light mode) */
+  --tool-header-bg: #DBEFFF;
+  --tool-header-border: #BEE2FF;
+  --tool-header-text: #1E88E5;
+  --tool-header-badge-bg: #C0DDFF;
+  --tool-header-badge-text: #004E99;
+
+  /* Subcategory title styling (light mode) */
+  --tool-subcategory-text-color: #9CA3AF; /* lighter text */
+  --tool-subcategory-rule-color: #E5E7EB; /* doubly lighter rule line */
   --accent-interactive: #4A90E2;
   --text-instruction: #4A90E2;
   --text-brand: var(--color-gray-700);
   --text-brand-accent: #DC2626;
 
+  /* Placeholder text colors */
+  --search-text-and-icon-color: #6B7382;
+
+  /* Tool panel search bar background colors */
+  --tool-panel-search-bg: #EFF1F4;
+  --tool-panel-search-border-bottom: #EFF1F4;
+
   /* container */
   --landing-paper-bg: var(--bg-surface);
   --landing-inner-paper-bg: #EEF8FF;
@@ -177,7 +197,7 @@
   --bg-raised: #1F2329;
   --bg-muted: #1F2329;
   --bg-background: #2A2F36;
-  --bg-toolbar: #272A2E;
+  --bg-toolbar: #1F2329;
   --bg-file-manager: #1F2329;
   --bg-file-list: #2A2F36;
   --btn-open-file: #0A8BFF;
@@ -185,7 +205,7 @@
   --text-secondary: #d1d5db;
   --text-muted: #9ca3af;
   --border-subtle: #2A2F36;
-  --border-default: #374151;
+  --border-default: #3A4047;
   --border-strong: #4b5563;
   --hover-bg: #374151;
   --active-bg: #4b5563;
@@ -251,6 +271,27 @@
   --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
   --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.4);
   --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.4);
+
+  --tools-text-and-icon-color: #D0D6DC;
+
+  /* Tool picker sticky header variables (dark mode) */
+  --tool-header-bg: #2A2F36;
+  --tool-header-border: #3A4047;
+  --tool-header-text: #D0D6DC;
+  --tool-header-badge-bg: #4B525A;
+  --tool-header-badge-text: #FFFFFF;
+
+  /* Subcategory title styling (dark mode) */
+  --tool-subcategory-text-color: #9CA3AF; /* lighter text in dark mode as well */
+  --tool-subcategory-rule-color: #3A4047; /* doubly lighter (relative) line in dark */
+
+  /* Placeholder text colors (dark mode) */
+  --search-text-and-icon-color: #FFFFFF !important;
+
+  /* Tool panel search bar background colors (dark mode) */
+  --tool-panel-search-bg: #1F2329;
+  --tool-panel-search-border-bottom: #4B525A;
+
 }
 
 /* Dropzone drop state styling */