Add frontend autoformatting and set CI to require formatted code for all languages (#6052)

# Description of Changes
Changes the strategy for autoformatting to reject PRs if they are not
formatted correctly instead of allowing them to merge and then spawning
a new PR to fix the formatting. The old strategy just caused more work
for us because we'd have to manually approve the followup PR and get it
merged, which required 2 reviewers so in practice it rarely got done and
just meant everyone's PRs ended up containing reformatting for unrelated
files, which makes code review unnecessarily difficult. If the PR's code
is not formatted correctly after this PR, a comment will be added
automatically to tell the author how to run the formatter script to fix
their code so it can go in.

This also enables autoformatting for the frontend code, using Prettier.
I've enabled it for pretty much everything in the frontend folder, other
than 3rd party files and files it doesn't make sense for. I also
excluded Markdown because it sounds likely to be more annoying to have
to autoformat the Markdown in the frontend folder but nowhere else. Open
to changing this though if people disagree.

> [!note]
> 
> Advice to reviewers: The first commit contains all of the actual logic
I've introduced (CI changes, Prettier config, etc.)
> The second commit is just the reformatting of the entire frontend
folder.
> The first commit needs proper review, the second one just give it a
spot-check that it's doing what you'd expect.

frontend/scripts/sample-pdf/generate.mjs

@@ -8,20 +8,20 @@
  * for users to experiment with Stirling PDF's features.
  */
 
-import puppeteer from 'puppeteer';
-import { fileURLToPath } from 'url';
-import { dirname, join } from 'path';
-import { existsSync, mkdirSync, statSync } from 'fs';
+import puppeteer from "puppeteer";
+import { fileURLToPath } from "url";
+import { dirname, join } from "path";
+import { existsSync, mkdirSync, statSync } from "fs";
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
 
-const TEMPLATE_PATH = join(__dirname, 'template.html');
-const OUTPUT_DIR = join(__dirname, '../../public/samples');
-const OUTPUT_PATH = join(OUTPUT_DIR, 'Sample.pdf');
+const TEMPLATE_PATH = join(__dirname, "template.html");
+const OUTPUT_DIR = join(__dirname, "../../public/samples");
+const OUTPUT_PATH = join(OUTPUT_DIR, "Sample.pdf");
 
 async function generatePDF() {
-  console.log('🚀 Starting Stirling PDF sample document generation...\n');
+  console.log("🚀 Starting Stirling PDF sample document generation...\n");
 
   // Ensure output directory exists
   if (!existsSync(OUTPUT_DIR)) {
@@ -40,66 +40,65 @@ async function generatePDF() {
   let browser;
   try {
     // Launch Puppeteer
-    console.log('🌐 Launching browser...');
+    console.log("🌐 Launching browser...");
     browser = await puppeteer.launch({
-      headless: 'new',
-      args: ['--no-sandbox', '--disable-setuid-sandbox']
+      headless: "new",
+      args: ["--no-sandbox", "--disable-setuid-sandbox"],
     });
 
     const page = await browser.newPage();
 
     // Set viewport to match A4 proportions
     await page.setViewport({
-      width: 794,  // A4 width in pixels at 96 DPI
+      width: 794, // A4 width in pixels at 96 DPI
       height: 1123, // A4 height in pixels at 96 DPI
-      deviceScaleFactor: 2 // Higher quality rendering
+      deviceScaleFactor: 2, // Higher quality rendering
     });
 
     // Navigate to the template file
     const fileUrl = `file://${TEMPLATE_PATH}`;
-    console.log('📖 Loading HTML template...');
+    console.log("📖 Loading HTML template...");
     await page.goto(fileUrl, {
-      waitUntil: 'networkidle0' // Wait for all resources to load
+      waitUntil: "networkidle0", // Wait for all resources to load
     });
 
     // Generate PDF with A4 dimensions
-    console.log('📝 Generating PDF...');
+    console.log("📝 Generating PDF...");
     await page.pdf({
       path: OUTPUT_PATH,
-      format: 'A4',
+      format: "A4",
       printBackground: true,
       margin: {
         top: 0,
         right: 0,
         bottom: 0,
-        left: 0
+        left: 0,
       },
-      preferCSSPageSize: true
+      preferCSSPageSize: true,
     });
 
-    console.log('\n✅ PDF generated successfully!');
+    console.log("\n✅ PDF generated successfully!");
     console.log(`📦 Output: ${OUTPUT_PATH}`);
 
     // Get file size
     const stats = statSync(OUTPUT_PATH);
     const fileSizeInKB = (stats.size / 1024).toFixed(2);
     console.log(`📊 File size: ${fileSizeInKB} KB`);
-
   } catch (error) {
-    console.error('\n❌ Error generating PDF:', error.message);
+    console.error("\n❌ Error generating PDF:", error.message);
     process.exit(1);
   } finally {
     if (browser) {
       await browser.close();
-      console.log('🔒 Browser closed.');
+      console.log("🔒 Browser closed.");
     }
   }
 
-  console.log('\n🎉 Done! Sample PDF is ready for use in Stirling PDF.\n');
+  console.log("\n🎉 Done! Sample PDF is ready for use in Stirling PDF.\n");
 }
 
 // Run the generator
-generatePDF().catch(error => {
-  console.error('Fatal error:', error);
+generatePDF().catch((error) => {
+  console.error("Fatal error:", error);
   process.exit(1);
 });