fix: AVIF sidecar crash, edit-metadata silent no-op, passport batch blank images, color-palette hex overflow, OCR log noise

- Convert all AI bridge inputs to PNG before writing to disk so PIL can
  read AVIF/WebP/TIFF (7 bridge files; face-detection and OCR already
  had this pattern)
- Add title/author aliases to edit-metadata schema so common field names
  actually write EXIF tags instead of being silently stripped by Zod
- Port extend/pad crop logic from passport-photo single endpoint to the
  batch pipeline so crop regions extending beyond the image get filled
  with background color instead of producing all-white output
- Clamp quantized color channels to 255 in color-palette to prevent
  Math.round(255/16)*16=256 from producing invalid hex like #100100100
- Compare OCR fallback warning against expected engine name per tier
  instead of comparing engine name against tier name (always mismatch)

apps/api/src/lib/exiftool.ts

@@ -137,6 +137,8 @@ export async function writeMetadata(
 
 /** Settings shape that buildTagArgs accepts */
 export interface EditMetadataSettings {
+  title?: string;
+  author?: string;
   artist?: string;
   copyright?: string;
   imageDescription?: string;
@@ -165,11 +167,16 @@ export interface EditMetadataSettings {
 export function buildTagArgs(settings: EditMetadataSettings): string[] {
   const args: string[] = [];
 
+  // Common aliases
+  const artist = settings.artist || settings.author;
+  const description = settings.imageDescription || settings.title;
+
   // Basic EXIF fields
-  if (settings.artist) args.push(`-Artist=${settings.artist}`);
+  if (artist) args.push(`-Artist=${artist}`);
   if (settings.copyright) args.push(`-Copyright=${settings.copyright}`);
-  if (settings.imageDescription) args.push(`-ImageDescription=${settings.imageDescription}`);
+  if (description) args.push(`-ImageDescription=${description}`);
   if (settings.software) args.push(`-Software=${settings.software}`);
+  if (settings.title) args.push(`-XMP:Title=${settings.title}`);
 
   // Date fields
   if (settings.dateTime) args.push(`-ModifyDate=${settings.dateTime}`);