fix: add server-side logging to AI tool routes (#23)

AI routes (remove-background, erase-object, ocr, blur-faces, upscale)
were silently swallowing errors - failures returned HTTP 422 to the
client but never appeared in server logs. This made it impossible for
self-hosters to diagnose issues like 504 timeouts from reverse proxies.

Adds request.log.info() at processing start (tool name, image size, key
settings) and request.log.error() in catch blocks, matching the existing
tool-factory pattern.

Co-authored-by: Siddharth Kumar Sah <siddharth123sk@gmail.com>

apps/api/src/routes/tools/erase-object.ts

@@ -63,6 +63,10 @@ export function registerEraseObject(app: FastifyInstance) {
     }
 
     try {
+      request.log.info(
+        { toolId: "erase-object", imageSize: imageBuffer.length, maskSize: maskBuffer.length },
+        "Starting object erasure",
+      );
       const jobId = randomUUID();
       const workspacePath = await createWorkspace(jobId);
 
@@ -110,6 +114,7 @@ export function registerEraseObject(app: FastifyInstance) {
         processedSize: resultBuffer.length,
       });
     } catch (err) {
+      request.log.error({ err, toolId: "erase-object" }, "Object erasing failed");
       return reply.status(422).send({
         error: "Object erasing failed",
         details: err instanceof Error ? err.message : "Unknown error",