feat: add table detection options and scan artifact removal

- Add TableDetectionSelector component for wired/wireless/region detection
- Add CV-based table line detector module (disabled due to poor performance)
- Add scan artifact removal preprocessing step (removes faint horizontal lines)
- Add PreprocessingConfig schema with remove_scan_artifacts option
- Update frontend PreprocessingSettings with scan artifact toggle
- Integrate table detection config into ProcessingPage
- Archive extract-table-cell-boxes proposal

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

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

frontend/src/i18n/locales/zh-TW.json

@@ -64,6 +64,16 @@
       "recommended": "推薦",
       "note": "版面模型會影響文件結構（表格、文字區塊、圖片）的偵測效果。請根據您的文件類型選擇適合的模型。"
     },
+    "tableDetection": {
+      "title": "表格偵測模式",
+      "wired": "有框線表格",
+      "wiredDesc": "偵測有明顯格線邊框的表格，適用於正式表格文件",
+      "wireless": "無框線表格",
+      "wirelessDesc": "偵測無邊框的表格，透過對齊方式推斷表格結構",
+      "region": "區域偵測",
+      "regionDesc": "輔助偵測表格區域，改善複雜表格的儲存格識別",
+      "note": "可同時啟用多種偵測模式，系統會自動整合偵測結果。如果表格儲存格框線不正確，請嘗試調整偵測模式。"
+    },
     "preprocessing": {
       "title": "影像前處理",
       "mode": {
@@ -92,6 +102,8 @@
         "strong": "強",
         "maximum": "最強"
       },
+      "removeScanArtifacts": "移除掃描瑕疵",
+      "removeScanArtifactsDesc": "移除掃描時光源產生的水平線痕，避免被誤判為表格框線",
       "advanced": "進階選項",
       "binarize": "二值化處理",
       "binarizeWarning": "不建議使用",