feat(account): add editable phone and password change with validation

- Add editable phone field in /account General tab with UK phone
  validation
- Create PUT /api/user/change-password endpoint in backend
- Add zxcvbn password strength meter to change password modal
- Add "passwords don't match" validation message to both /account and
  /register
- Fix navbar logout reactivity with invalidateAll and $derived values
- Fix a11y warnings: add labels, roles, and keyboard handlers
- Remove unused CSS from account page

frontend/src/lib/components/admin/ApprovalModal.svelte

@@ -416,27 +416,14 @@
 </AlertDialog.Root>
 
 <style>
-	/* Hide number input arrows for Chrome, Safari, Edge */
-	input.no-spin::-webkit-outer-spin-button,
-	input.no-spin::-webkit-inner-spin-button {
-		-webkit-appearance: none;
-		margin: 0;
-	}
-
-	/* Hide number input arrows for Firefox */
-	input.no-spin[type='number'] {
+	/* Hide number input arrows for all number inputs in the component */
+	:global(input[type='number']) {
 		-moz-appearance: textfield;
 		appearance: textfield;
 	}
 
-	/* Remove arrows from all number inputs in the component */
-	input[type='number'] {
-		-moz-appearance: textfield;
-		appearance: textfield;
-	}
-
-	input[type='number']::-webkit-outer-spin-button,
-	input[type='number']::-webkit-inner-spin-button {
+	:global(input[type='number']::-webkit-outer-spin-button),
+	:global(input[type='number']::-webkit-inner-spin-button) {
 		-webkit-appearance: none;
 		margin: 0;
 	}

frontend/src/lib/components/admin/ImageUpload.svelte

@@ -440,7 +440,7 @@
 		</div>
 
 		<div class="space-y-1">
-			<label class="text-sm font-medium text-gray-700">Tags</label>
+			<label for="tag-input" class="text-sm font-medium text-gray-700">Tags</label>
 
 			<div class="relative">
 				<div
@@ -494,6 +494,9 @@
 									? 'bg-primary/10 text-primary font-medium'
 									: 'hover:bg-gray-100'}"
 								onclick={() => selectSuggestion(s)}
+								onkeydown={(e) => (e.key === 'Enter' || e.key === ' ') && selectSuggestion(s)}
+								role="button"
+								tabindex="0"
 							>
 								{s}
 							</div>