feat: full HEIF/HEIC support, content-aware resize performance fix, UI improvements

- Add bidirectional HEIF support: decode (input) and encode (output) via system heif-convert/heif-enc
- Add server-side WebP preview generation for non-browser-previewable formats (HEIC, TIFF)
- Fix content-aware resize failing on HEIF input (decode before passing to caire)
- Fix content-aware resize timeout on large images by downscaling to max 1200px and using JPEG intermediate
- Add HEIF as target format in convert tool
- Add loading spinner for HEIF preview decode in file store
- Fix file picker not accepting HEIF files (explicit .heic,.heif,.hif extensions)
- Extend frontend timeout for medium tools to 180s with 45s progress animation
- Redesign rotate controls with preset buttons and compact flip section
- Remove misleading savings percentage from convert tool

apps/api/src/lib/file-validation.ts

@@ -154,11 +154,13 @@ function detectMagicBytes(buffer: Buffer): string | null {
         const brand = buffer.slice(8, 12).toString("ascii");
         if (brand !== "avif" && brand !== "avis") continue;
       }
-      // For ftyp, verify HEIF/HEIC brand at bytes 8-11
+      // For ftyp, verify HEIF/HEIC brand at bytes 8-11.
+      // Covers HEVC still (heic/heix), HEVC sequence (hevc/hevx),
+      // generic HEIF still/sequence (mif1/msf1), and multi-layer profiles.
       if (entry.format === "heif") {
         if (buffer.length < 12) continue;
         const brand = buffer.slice(8, 12).toString("ascii");
-        if (brand !== "heic" && brand !== "heix" && brand !== "mif1") continue;
+        if (!["heic", "heix", "mif1", "msf1", "hevc", "hevx"].includes(brand)) continue;
       }
       return entry.format;
     }

apps/api/src/lib/heic-converter.ts

@@ -8,9 +8,8 @@ import { promisify } from "node:util";
 const execFileAsync = promisify(execFile);
 
 /**
- * Find the HEIF decode command. macOS (Homebrew) provides `heif-dec`,
- * while Linux packages provide `heif-convert`. Both accept the same
- * `<input> <output>` argument syntax.
+ * Find the HEIF decode command. Both heif-convert and heif-dec accept
+ * `<input> <output>` positional arguments.
  */
 let cachedDecodeCmd: string | null = null;
 
@@ -32,20 +31,32 @@ async function findDecodeCmd(): Promise<string> {
  * Decode a HEIC/HEIF buffer to PNG using the system HEIF decoder CLI.
  * This is needed because Sharp's bundled libheif does not include the
  * HEVC decoder required for true HEIC files (iPhone photos).
+ *
+ * Multi-image HEIF files (common from iPhones) cause heif-convert/heif-dec
+ * to add numeric suffixes (-1, -2, ...) to the output filename. We try the
+ * exact path first, then fall back to the -1 suffixed path.
  */
 export async function decodeHeic(buffer: Buffer): Promise<Buffer> {
   const cmd = await findDecodeCmd();
   const id = randomUUID();
   const inputPath = join(tmpdir(), `heic-in-${id}.heic`);
   const outputPath = join(tmpdir(), `heic-out-${id}.png`);
+  const suffixedPath = outputPath.replace(/\.png$/, "-1.png");
 
   try {
     await writeFile(inputPath, buffer);
     await execFileAsync(cmd, [inputPath, outputPath], { timeout: 30_000 });
-    return await readFile(outputPath);
+
+    // Single-image HEIF: exact filename. Multi-image: -1 suffix on first image.
+    try {
+      return await readFile(outputPath);
+    } catch {
+      return await readFile(suffixedPath);
+    }
   } finally {
     await rm(inputPath, { force: true }).catch(() => {});
     await rm(outputPath, { force: true }).catch(() => {});
+    await rm(suffixedPath, { force: true }).catch(() => {});
   }
 }