feat: comprehensive HEIC/HEIF support and edit-metadata ExifTool overhaul

- Add ensureSharpCompat() helper for automatic HEIC detection and decode
- Fix HEIC support in all 14 custom-route tools (image-to-pdf, split,
  barcode-read, compose, collage, stitch, compare, find-duplicates,
  color-palette, watermark-image, vectorize, favicon, info, branding)
- Fix PdfPagePreview using store's decoded blobUrl instead of raw File
- Add onError fallback in ImageViewer for unrenderable formats
- Fix image-to-pdf progress bar with flushSync for reliable rendering
- Add ExifTool backend for edit-metadata (GPS, keywords, IPTC, dates)
- Rename Strip Metadata to Remove Metadata with interactive Leaflet map
- Fix user-files thumbnail generation for stored HEIC files
- Fix info tool stats() histogram for HEIC via decoded buffer
- Skip HEIC preprocessing in batch route for metadata tools

apps/api/src/routes/tools/compose.ts

@@ -5,6 +5,7 @@ import type { FastifyInstance } from "fastify";
 import sharp from "sharp";
 import { z } from "zod";
 import { sanitizeFilename } from "../../lib/filename.js";
+import { ensureSharpCompat } from "../../lib/heic-converter.js";
 import { createWorkspace } from "../../lib/workspace.js";
 
 const settingsSchema = z.object({
@@ -80,6 +81,10 @@ export function registerCompose(app: FastifyInstance) {
     }
 
     try {
+      // Decode HEIC/HEIF if needed
+      baseBuffer = await ensureSharpCompat(baseBuffer);
+      overlayBuffer = await ensureSharpCompat(overlayBuffer);
+
       // Apply opacity to overlay if needed
       let processedOverlay = overlayBuffer;
       if (settings.opacity < 100) {