fix(image): decode real iPhone HEIC files instead of rejecting them at validation (#631)

validateImageBuffer() never listed heif in CLI_DECODED_FORMATS, so real iPhone HEIC uploads hit Sharp's own metadata probe (its bundled libheif only supports AV1/AVIF) and got rejected before reaching the working heif-convert/heif-dec decode path already wired up downstream. Adds heif to that set, same as raw/psd/tga/bmp/etc.

Also fixes the same gap on erase-object's mask input, which validates through the same function but had no matching decode step, so a HEIC mask reached an unguarded sharp() call and came back as a misclassified server error instead of a clean 422.

Fixes #622

tests/unit/api/file-validation-mutation.test.ts

@@ -430,15 +430,17 @@ describe("validateImageBuffer - ftyp brand verification", () => {
     expectRejected(await validateImageBuffer(buf), "Unrecognized image format");
   });
 
+  // Uses a synthetic buffer, not a real fixture, because sharp's metadata()
+  // reads HEIF dimensions from the box-level `ispe` data and succeeds on real
+  // HEVC-coded fixtures regardless of codec support (only pixel decode needs
+  // it). A real fixture here would pass even without the fix below.
   const heifBrands = ["heic", "heix", "mif1", "msf1", "hevc", "hevx"];
   for (const brand of heifBrands) {
-    it(`accepts the heif brand "${brand}" (detected, then synthetic decode fails)`, async () => {
-      // Each brand must pass the L349 includes() check; on a synthetic buffer
-      // the format is heif (not CLI-decoded) and sharp fails -> metadata error.
-      expectRejected(
-        await validateImageBuffer(withFtypBrand(brand)),
-        "Failed to read image metadata",
-      );
+    it(`accepts the heif brand "${brand}" and returns early without a sharp decode`, async () => {
+      // Each brand must pass the L349 includes() check; heif is CLI-decoded
+      // (real HEVC decode happens later via decodeHeic()), so this must return
+      // valid immediately, the same as the CR3->raw arm below.
+      expectValid(await validateImageBuffer(withFtypBrand(brand)), "heif", 0, 0);
     });
   }