feat: implement hybrid image extraction and memory management

Backend:
- Add hybrid image extraction for Direct track (inline image blocks)
- Add render_inline_image_regions() fallback when OCR doesn't find images
- Add check_document_for_missing_images() for detecting missing images
- Add memory management system (MemoryGuard, ModelManager, ServicePool)
- Update pdf_generator_service to handle HYBRID processing track
- Add ElementType.LOGO for logo extraction

Frontend:
- Fix PDF viewer re-rendering issues with memoization
- Add TaskNotFound component and useTaskValidation hook
- Disable StrictMode due to react-pdf incompatibility
- Fix task detail and results page loading states

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

frontend/src/pages/TaskDetailPage.tsx

@@ -1,3 +1,4 @@
+import { useMemo } from 'react'
 import { useParams, useNavigate } from 'react-router-dom'
 import { useTranslation } from 'react-i18next'
 import { useQuery } from '@tanstack/react-query'
@@ -65,6 +66,19 @@ export default function TaskDetailPage() {
     retry: false,
   })
 
+  // Construct PDF URL for preview - memoize to prevent unnecessary reloads
+  // Must be called unconditionally before any early returns (React hooks rule)
+  const API_BASE_URL = import.meta.env.VITE_API_BASE_URL || 'http://localhost:8000'
+  const pdfUrl = useMemo(() => {
+    return taskId ? `${API_BASE_URL}/api/v2/tasks/${taskId}/download/pdf` : ''
+  }, [taskId, API_BASE_URL])
+
+  // Get auth token for PDF preview - memoize to prevent new object reference each render
+  const pdfHttpHeaders = useMemo(() => {
+    const authToken = localStorage.getItem('auth_token_v2')
+    return authToken ? { Authorization: `Bearer ${authToken}` } : undefined
+  }, [])
+
   const getTrackBadge = (track?: ProcessingTrack) => {
     if (!track) return null
     switch (track) {
@@ -218,14 +232,6 @@ export default function TaskDetailPage() {
   const isProcessing = taskDetail.status === 'processing'
   const isFailed = taskDetail.status === 'failed'
 
-  // Construct PDF URL for preview
-  const API_BASE_URL = import.meta.env.VITE_API_BASE_URL || 'http://localhost:8000'
-  const pdfUrl = taskId ? `${API_BASE_URL}/api/v2/tasks/${taskId}/download/pdf` : ''
-
-  // Get auth token for PDF preview
-  const authToken = localStorage.getItem('auth_token_v2')
-  const pdfHttpHeaders = authToken ? { Authorization: `Bearer ${authToken}` } : undefined
-
   return (
     <div className="space-y-6">
       {/* Page Header */}