fix: verbose error handling, batch processing, and multi-file support

- Replace [object Object] errors with readable messages across all 20+ API
  routes by normalizing Zod validation errors to strings (formatZodErrors)
- Add parseApiError() on frontend to defensively handle any details type
- Add global Fastify error handler with full stack traces in logs
- Fix image-to-pdf auth: Object.entries(headers) → headers.forEach()
- Fix passport-photo: safeParse + formatZodErrors, safe error extraction
- Fix OCR silent fallbacks: log exception type/message when falling back,
  include actual engine used in API response and Docker logs
- Fix split tool: process all uploaded images, combine into ZIP with
  subfolders per image
- Fix batch support for blur-faces, strip-metadata, edit-metadata,
  vectorize: add processAllFiles branch for multi-file uploads
- Docker: LOG_LEVEL=debug, PYTHONWARNINGS=default for visibility
- Add Playwright e2e tests verifying all fixes against Docker container

apps/web/src/hooks/use-pipeline-processor.ts

@@ -1,5 +1,5 @@
 import { useCallback, useEffect, useRef, useState } from "react";
-import { formatHeaders } from "@/lib/api";
+import { formatHeaders, parseApiError } from "@/lib/api";
 import { generateId } from "@/lib/utils";
 import { useFileStore } from "@/stores/file-store";
 import type { PipelineStep } from "@/stores/pipeline-store";
@@ -145,10 +145,7 @@ export function usePipelineProcessor() {
         } else {
           try {
             const body = JSON.parse(xhr.responseText);
-            const msg = body.details
-              ? `${body.error}: ${body.details}`
-              : body.error || `Processing failed: ${xhr.status}`;
-            setError(msg);
+            setError(parseApiError(body, xhr.status));
           } catch {
             setError(`Processing failed: ${xhr.status}`);
           }
@@ -273,9 +270,7 @@ export function usePipelineProcessor() {
                 errorMsg += ` (${body.errors.length} files failed)`;
               }
             } else {
-              errorMsg = body.details
-                ? `${body.error}: ${body.details}`
-                : body.error || `Batch processing failed: ${response.status}`;
+              errorMsg = parseApiError(body, response.status);
             }
           } catch {
             errorMsg = `Batch processing failed: ${response.status}`;

apps/web/src/hooks/use-tool-processor.ts

@@ -1,6 +1,6 @@
 import { PYTHON_SIDECAR_TOOLS } from "@ashim/shared";
 import { useCallback, useEffect, useRef, useState } from "react";
-import { formatHeaders } from "@/lib/api";
+import { formatHeaders, parseApiError } from "@/lib/api";
 import { generateId } from "@/lib/utils";
 import { useFileStore } from "@/stores/file-store";
 
@@ -233,10 +233,7 @@ export function useToolProcessor(toolId: string) {
         } else {
           try {
             const body = JSON.parse(xhr.responseText);
-            const msg = body.details
-              ? `${body.error}: ${body.details}`
-              : body.error || `Processing failed: ${xhr.status}`;
-            setError(msg);
+            setError(parseApiError(body, xhr.status));
           } catch {
             setError(`Processing failed: ${xhr.status}`);
           }
@@ -357,9 +354,7 @@ export function useToolProcessor(toolId: string) {
           let errorMsg: string;
           try {
             const body = JSON.parse(text);
-            errorMsg = body.details
-              ? `${body.error}: ${body.details}`
-              : body.error || `Batch processing failed: ${response.status}`;
+            errorMsg = parseApiError(body, response.status);
           } catch {
             errorMsg = `Batch processing failed: ${response.status}`;
           }