feat: add backend OCR manual proxy endpoint (refs #135)

Add POST /api/ocr/extract/manual endpoint that proxies to the Python
OCR service's manual extraction pipeline. Includes Pro tier gating via
document.scanMaintenanceSchedule, PDF-only validation, 200MB file size
limit, and async 202 job response for polling via existing job status
endpoint.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/features/ocr/external/ocr-client.ts

@@ -2,7 +2,7 @@
  * @ai-summary HTTP client for OCR service communication
  */
 import { logger } from '../../../core/logging/logger';
-import type { JobResponse, OcrResponse, ReceiptExtractionResponse, VinExtractionResponse } from '../domain/ocr.types';
+import type { JobResponse, ManualJobResponse, OcrResponse, ReceiptExtractionResponse, VinExtractionResponse } from '../domain/ocr.types';
 
 /** OCR service configuration */
 const OCR_SERVICE_URL = process.env.OCR_SERVICE_URL || 'http://mvp-ocr:8000';
@@ -265,6 +265,61 @@ export class OcrClient {
     return (await response.json()) as JobResponse;
   }
 
+  /**
+   * Submit an async manual extraction job for PDF owner's manuals.
+   *
+   * @param fileBuffer - PDF file buffer
+   * @param contentType - MIME type of the file (must be application/pdf)
+   * @param vehicleId - Optional vehicle ID for context
+   * @returns Manual job submission response
+   */
+  async submitManualJob(
+    fileBuffer: Buffer,
+    contentType: string,
+    vehicleId?: string
+  ): Promise<ManualJobResponse> {
+    const formData = this.buildFormData(fileBuffer, contentType);
+    if (vehicleId) {
+      formData.append('vehicle_id', vehicleId);
+    }
+
+    const url = `${this.baseUrl}/extract/manual`;
+
+    logger.info('OCR manual job submit request', {
+      operation: 'ocr.client.submitManualJob',
+      url,
+      contentType,
+      fileSize: fileBuffer.length,
+      hasVehicleId: !!vehicleId,
+    });
+
+    const response = await this.fetchWithTimeout(url, {
+      method: 'POST',
+      body: formData,
+    });
+
+    if (!response.ok) {
+      const errorText = await response.text();
+      logger.error('OCR manual job submit failed', {
+        operation: 'ocr.client.submitManualJob.error',
+        status: response.status,
+        error: errorText,
+      });
+      throw new Error(`OCR service error: ${response.status} - ${errorText}`);
+    }
+
+    const result = (await response.json()) as ManualJobResponse;
+
+    logger.info('OCR manual job submitted', {
+      operation: 'ocr.client.submitManualJob.success',
+      jobId: result.jobId,
+      status: result.status,
+      estimatedSeconds: result.estimatedSeconds,
+    });
+
+    return result;
+  }
+
   /**
    * Check if the OCR service is healthy.
    *