feat(web): in-canvas zoom & pan for the object eraser and split tools (#320)

* feat(web): add pure zoom/pan math module with unit tests

* feat(i18n): add a11y.pan key across all locales (English, matching adjacent zoom labels)

* feat(web): add useZoomPan hook (state + gestures over pure math)

* feat(web): add ZoomToolbar component

* feat(web): zoom & pan in the object eraser canvas

* feat(web): zoom & pan in the split tool preview

* fix(web): synchronous pan-mode refs so drag-pan is race-free under fast input

* test(e2e): zoom & pan acceptance (split always-on, eraser bundle-gated)

packages/shared/src/i18n/ar.ts

@@ -3398,6 +3398,7 @@ export const ar: TranslationKeys = {
     zoomOut: "تصغير",
     fitToView: "ملاءمة العرض",
     actualSize: "الحجم الفعلي",
+    pan: "تحريك",
     previousImage: "الملف السابق",
     nextImage: "الملف التالي",
     imageArea: "منطقة المعاينة",

packages/shared/src/i18n/de.ts

@@ -3440,6 +3440,7 @@ export const de: TranslationKeys = {
     zoomOut: "Verkleinern",
     fitToView: "Einpassen",
     actualSize: "Originalgröße",
+    pan: "Verschieben",
     previousImage: "Vorherige Datei",
     nextImage: "Nächste Datei",
     imageArea: "Vorschaubereich",

packages/shared/src/i18n/en.ts

@@ -3368,6 +3368,7 @@ export const en = {
     zoomOut: "Zoom out",
     fitToView: "Fit to view",
     actualSize: "Actual size",
+    pan: "Pan",
     previousImage: "Previous file",
     nextImage: "Next file",
     imageArea: "Preview area",

packages/shared/src/i18n/es.ts

@@ -3422,6 +3422,7 @@ export const es: TranslationKeys = {
     zoomOut: "Alejar",
     fitToView: "Ajustar a la vista",
     actualSize: "Tamaño real",
+    pan: "Desplazar",
     previousImage: "Archivo anterior",
     nextImage: "Siguiente archivo",
     imageArea: "Área de vista previa",

packages/shared/src/i18n/fr.ts

@@ -3446,6 +3446,7 @@ export const fr: TranslationKeys = {
     zoomOut: "Zoom arrière",
     fitToView: "Ajuster à la vue",
     actualSize: "Taille réelle",
+    pan: "Déplacer",
     previousImage: "Fichier précédent",
     nextImage: "Fichier suivant",
     imageArea: "Zone d'aperçu",

packages/shared/src/i18n/hi.ts

@@ -3393,6 +3393,7 @@ export const hi: TranslationKeys = {
     zoomOut: "ज़ूम आउट",
     fitToView: "दृश्य में फ़िट करें",
     actualSize: "वास्तविक आकार",
+    pan: "पैन करें",
     previousImage: "पिछली फ़ाइल",
     nextImage: "अगली फ़ाइल",
     imageArea: "पूर्वावलोकन क्षेत्र",

packages/shared/src/i18n/id.ts

@@ -3421,6 +3421,7 @@ export const id: TranslationKeys = {
     zoomOut: "Perkecil",
     fitToView: "Sesuaikan tampilan",
     actualSize: "Ukuran asli",
+    pan: "Geser",
     previousImage: "Previous image",
     nextImage: "Next image",
     imageArea: "Image area",

packages/shared/src/i18n/it.ts

@@ -3435,6 +3435,7 @@ export const it: TranslationKeys = {
     zoomOut: "Riduci",
     fitToView: "Adatta alla vista",
     actualSize: "Dimensione reale",
+    pan: "Sposta",
     previousImage: "Immagine precedente",
     nextImage: "Immagine successiva",
     imageArea: "Area immagine",

packages/shared/src/i18n/ja.ts

@@ -3373,6 +3373,7 @@ export const ja: TranslationKeys = {
     zoomOut: "縮小",
     fitToView: "画面に合わせる",
     actualSize: "実寸表示",
+    pan: "移動",
     previousImage: "Previous image",
     nextImage: "Next image",
     imageArea: "Image area",

packages/shared/src/i18n/ko.ts

@@ -3355,6 +3355,7 @@ export const ko: TranslationKeys = {
     zoomOut: "축소",
     fitToView: "화면에 맞추기",
     actualSize: "실제 크기",
+    pan: "이동",
     previousImage: "Previous image",
     nextImage: "Next image",
     imageArea: "Image area",

packages/shared/src/i18n/nl.ts

@@ -3429,6 +3429,7 @@ export const nl: TranslationKeys = {
     zoomOut: "Uitzoomen",
     fitToView: "Passend in beeld",
     actualSize: "Werkelijke grootte",
+    pan: "Verschuiven",
     previousImage: "Previous image",
     nextImage: "Next image",
     imageArea: "Image area",

packages/shared/src/i18n/pl.ts

@@ -3437,6 +3437,7 @@ export const pl: TranslationKeys = {
     zoomOut: "Pomniejsz",
     fitToView: "Dopasuj do widoku",
     actualSize: "Rzeczywisty rozmiar",
+    pan: "Przesuń",
     previousImage: "Poprzedni plik",
     nextImage: "Następny plik",
     imageArea: "Obszar podglądu",

packages/shared/src/i18n/pt-BR.ts

@@ -3429,6 +3429,7 @@ export const ptBR: TranslationKeys = {
     zoomOut: "Diminuir zoom",
     fitToView: "Ajustar à tela",
     actualSize: "Tamanho real",
+    pan: "Mover",
     previousImage: "Arquivo anterior",
     nextImage: "Próximo arquivo",
     imageArea: "Área de visualização",

packages/shared/src/i18n/ru.ts

@@ -3424,6 +3424,7 @@ export const ru: TranslationKeys = {
     zoomOut: "Уменьшить",
     fitToView: "Вписать в окно",
     actualSize: "Реальный размер",
+    pan: "Перемещение",
     previousImage: "Предыдущий файл",
     nextImage: "Следующий файл",
     imageArea: "Область предпросмотра",

packages/shared/src/i18n/sv.ts

@@ -3416,6 +3416,7 @@ export const sv: TranslationKeys = {
     zoomOut: "Zooma ut",
     fitToView: "Anpassa till vy",
     actualSize: "Verklig storlek",
+    pan: "Panorera",
     previousImage: "Föregående fil",
     nextImage: "Nästa fil",
     imageArea: "Förhandsvisningsområde",

packages/shared/src/i18n/th.ts

@@ -3379,6 +3379,7 @@ export const th: TranslationKeys = {
     zoomOut: "ซูมออก",
     fitToView: "พอดีกับหน้าจอ",
     actualSize: "ขนาดจริง",
+    pan: "เลื่อน",
     previousImage: "ไฟล์ก่อนหน้า",
     nextImage: "ไฟล์ถัดไป",
     imageArea: "พื้นที่แสดงตัวอย่าง",

packages/shared/src/i18n/tr.ts

@@ -3431,6 +3431,7 @@ export const tr: TranslationKeys = {
     zoomOut: "Uzaklaştır",
     fitToView: "Görünüme sığdır",
     actualSize: "Gerçek boyut",
+    pan: "Kaydır",
     previousImage: "Önceki dosya",
     nextImage: "Sonraki dosya",
     imageArea: "Önizleme alanı",

packages/shared/src/i18n/uk.ts

@@ -3426,6 +3426,7 @@ export const uk: TranslationKeys = {
     zoomOut: "Зменшити",
     fitToView: "Вписати у вікно",
     actualSize: "Справжній розмір",
+    pan: "Переміщення",
     previousImage: "Попередній файл",
     nextImage: "Наступний файл",
     imageArea: "Область попереднього перегляду",

packages/shared/src/i18n/vi.ts

@@ -3417,6 +3417,7 @@ export const vi: TranslationKeys = {
     zoomOut: "Thu nhỏ",
     fitToView: "Vừa khung nhìn",
     actualSize: "Kích thước thực",
+    pan: "Di chuyển",
     previousImage: "Tệp trước",
     nextImage: "Tệp tiếp theo",
     imageArea: "Vùng xem trước",

packages/shared/src/i18n/zh-CN.ts

@@ -3328,6 +3328,7 @@ export const zhCN: TranslationKeys = {
     zoomOut: "缩小",
     fitToView: "适应视图",
     actualSize: "实际大小",
+    pan: "平移",
     previousImage: "上一个文件",
     nextImage: "下一个文件",
     imageArea: "预览区域",

packages/shared/src/i18n/zh-TW.ts

@@ -3328,6 +3328,7 @@ export const zhTW: TranslationKeys = {
     zoomOut: "縮小",
     fitToView: "符合檢視大小",
     actualSize: "實際大小",
+    pan: "平移",
     previousImage: "上一個檔案",
     nextImage: "下一個檔案",
     imageArea: "預覽區域",