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

scripts/test-docker-fixes.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+set -e
+
+echo "=== Step 1: Stop existing container ==="
+docker stop ashim 2>/dev/null || true
+docker rm ashim 2>/dev/null || true
+
+echo "=== Step 2: Start test container ==="
+docker run -d \
+  --name ashim-test \
+  -p 1349:1349 \
+  -e AUTH_ENABLED=true \
+  -e DEFAULT_USERNAME=admin \
+  -e DEFAULT_PASSWORD=admin \
+  -e LOG_LEVEL=debug \
+  -e RATE_LIMIT_PER_MIN=50000 \
+  -e SKIP_MUST_CHANGE_PASSWORD=true \
+  ashim:test-fixes
+
+echo "=== Step 3: Wait for container to be healthy ==="
+echo "Waiting for health check..."
+for i in $(seq 1 60); do
+  STATUS=$(docker inspect --format='{{.State.Health.Status}}' ashim-test 2>/dev/null || echo "starting")
+  if [ "$STATUS" = "healthy" ]; then
+    echo "Container is healthy after ${i}0 seconds"
+    break
+  fi
+  if [ "$STATUS" = "unhealthy" ]; then
+    echo "Container is unhealthy!"
+    docker logs ashim-test --tail 50
+    exit 1
+  fi
+  echo "  Status: $STATUS (${i}0s elapsed)"
+  sleep 10
+done
+
+echo "=== Step 4: Run Playwright tests ==="
+npx playwright test --config playwright.docker.config.ts --reporter=list 2>&1
+
+TEST_EXIT=$?
+
+echo "=== Step 5: Check Docker logs for errors ==="
+echo "--- Container logs (last 50 lines) ---"
+docker logs ashim-test --tail 50
+
+echo "=== Step 6: Cleanup ==="
+docker stop ashim-test
+docker rm ashim-test
+
+# Restart original container
+echo "=== Restarting original ashim container ==="
+docker start ashim 2>/dev/null || true
+
+exit $TEST_EXIT