Add PDF translation API, utilities, docs, and config

Introduces core backend and frontend infrastructure for a PDF translation interface. Adds API endpoints for translation, PDF testing, and AI provider testing; implements PDF text extraction, cost tracking, and pricing logic in the lib directory; adds reusable UI components; and provides comprehensive documentation (SDD, environment setup, Claude instructions). Updates Tailwind and global styles, and includes a sample test PDF and configuration files.

create-test-pdf.js

@@ -0,0 +1,55 @@
+const fs = require('fs')
+const { PDFDocument, StandardFonts, rgb } = require('pdf-lib')
+
+async function createTestPDF() {
+  try {
+    // Create a new PDF document using pdf-lib (same library we use for processing)
+    const pdfDoc = await PDFDocument.create()
+    
+    // Add a page
+    const page = pdfDoc.addPage()
+    const { width, height } = page.getSize()
+    
+    // Embed a standard font
+    const font = await pdfDoc.embedFont(StandardFonts.Helvetica)
+    
+    // Add text content (using only ASCII characters to ensure compatibility)
+    const fontSize = 16
+    let yPosition = height - 100
+    
+    const texts = [
+      'PDF Text Extraction Test',
+      'This is a test document for PDF text extraction.',
+      'Line 1: Hello World',
+      'Line 2: Testing PDF processing',
+      'Line 3: Multiple line text extraction',
+      'This PDF was created using pdf-lib.',
+      'It should have extractable text content.'
+    ]
+    
+    for (const text of texts) {
+      page.drawText(text, {
+        x: 50,
+        y: yPosition,
+        size: fontSize,
+        font: font,
+        color: rgb(0, 0, 0),
+      })
+      yPosition -= fontSize + 10
+    }
+    
+    // Save the PDF
+    const pdfBytes = await pdfDoc.save()
+    
+    // Write to file
+    fs.writeFileSync('test-document.pdf', pdfBytes)
+    
+    console.log('Test PDF created successfully: test-document.pdf')
+    console.log(`PDF size: ${pdfBytes.length} bytes`)
+    
+  } catch (error) {
+    console.error('Error creating PDF:', error)
+  }
+}
+
+createTestPDF()