feat: add theme provider and control components for light/dark mode

- Implemented ThemeProvider to manage theme state and preferences.
- Added ThemeControl component for users to switch between system, light, and dark themes.
- Integrated localStorage for theme preference persistence.
- Updated document styles based on theme changes.

test: add tests for permanent deletion of habits and related records

- Created tests to ensure permanent deletion of habits removes all dependent records.
- Verified that deletion requires ownership, authentication, and checks for archived habits.
- Added tests to confirm rollback behavior on deletion failures.

test: add tests for habit palette and progress card functionality

- Implemented tests for habit color progression and theme-based color shading.
- Added tests for progress card calculations and calendar display logic.

feat: define theme types and preferences

- Introduced Theme and ThemePreference types for better type safety.
- Created utility functions for resolving theme based on user preference and system settings.
- Defined theme palettes for light and dark modes to ensure adequate contrast.

src/pages/Home.tsx

@@ -1,4 +1,4 @@
-import { Archive, Settings2 } from "lucide-react";
+import { Archive, Plus, Settings2 } from "lucide-react";
 import { ArchivedHabits } from "../components/ArchivedHabits";
 import { AccountSettings } from "../components/AccountSettings";
 import { useCallback, useEffect, useRef, useState } from "react";
@@ -442,7 +442,6 @@ function Dashboard({ user, onExpired }: { user: PublicUser; onExpired: () => voi
             >
               <div className="ds-section-top">
                 <SectionHeading
-                  number="YOUR HABITS"
                   id="habits-title"
                   title={
                     <>
@@ -581,7 +580,7 @@ function SavedHabit({
                   disabled={disabled || habit.requirements.tasks.length >= 100}
                   onClick={() => setAddingTask(true)}
                 >
-                  Add task +
+                  <Plus size={20} aria-hidden="true" /><span>Add task</span>
                 </Button>
               </div>
           </>