fix: critical SVG XSS vulnerability in file uploads

- Add comprehensive file type validation to prevent SVG uploads
- Update upload widgets to restrict file types at input level
- Enhanced HTML sanitization to block SVG tags and data URLs
- Create centralized file validation utilities with shared constants
- Add client-side and server-side protection against malicious uploads

Security Impact:
- Prevents stored XSS attacks through malicious SVG profile uploads
- Blocks execution of JavaScript embedded in SVG files
- Enforces whitelist of safe image formats (JPEG, PNG, GIF, WebP)
- Provides defense-in-depth protection across all upload components

Fixes reported vulnerability in profile image upload functionality.

apps/dashboard/src/lib/components/UploadImage/index.svelte

@@ -3,6 +3,7 @@
   import { Loading } from 'carbon-components-svelte';
   import Camera from 'carbon-icons-svelte/lib/Camera.svelte';
   import { createEventDispatcher } from 'svelte';
+  import { validateImageUpload } from '$lib/utils/functions/fileValidation';
 
   export let avatar: string | undefined;
   export let src: string | undefined;
@@ -19,13 +20,24 @@
 
   const onFileSelected = (e: Event<HTMLInputElement>) => {
     const image = e.target.files[0];
+    
+    // Validate file type first (security check)
+    const validation = validateImageUpload(image);
+    if (!validation.isValid) {
+      errorMessage = validation.error;
+      fileinput.value = ''; // Clear the input
+      return;
+    }
+    
     const maxFileSize = maxFileSizeInMb * 1024 * 1024;
     if (image.size > maxFileSize) {
       errorMessage = `${$t('settings.profile.profile_picture.validation_error')} ${
         maxFileSize / (1024 * 1024)
       } MB`;
+      fileinput.value = ''; // Clear the input
       return;
     }
+    
     let reader = new FileReader();
     reader.readAsDataURL(image);
     reader.onload = (e) => {

apps/dashboard/src/lib/components/UploadWidget/index.svelte

@@ -9,6 +9,7 @@
   import { queryUnsplash } from './utils';
   import PrimaryButton from '$lib/components/PrimaryButton/index.svelte';
   import { t } from '$lib/utils/functions/translations';
+  import { validateImageUpload } from '$lib/utils/functions/fileValidation';
 
   export let imageURL = '';
 
@@ -47,6 +48,16 @@
 
   const onFileSelected = () => {
     const file = fileInput?.files?.[0];
+    if (!file) return;
+    
+    const validation = validateImageUpload(file);
+    if (!validation.isValid) {
+      snackbar.error(validation.error || 'Invalid file type');
+      label = $t('snackbar.landing_page_settings.error.try_again');
+      fileInput.value = '';
+      return;
+    }
+
     const sizeInkb = file?.size! / 1024;
     if (sizeInkb > 500) {
       snackbar.error('snackbar.landing_page_settings.error.file_size');
@@ -115,6 +126,7 @@
           <div class="w-full">
             <input
               type="file"
+              accept=".jpg,.jpeg,.png,.gif,.webp,image/jpeg,image/png,image/gif,image/webp"
               style="display: none;"
               bind:this={fileInput}
               on:change={onFileSelected}