feat(i18n): localize Stories tab (list, content, dialogs, toasts)

Covers the title + "New Story" button, empty states, story row
metadata (item count, updated time), the create/edit/delete dialogs,
and all toast notifications. Also handles StoryContent: "Select a
story" placeholder, search popover, "Export Audio" button, and the
"Generating N audios" pending indicator.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

app/src/i18n/locales/en/translation.json

@@ -37,6 +37,80 @@
       "deleting": "Deleting…"
     }
   },
+  "stories": {
+    "title": "Stories",
+    "newStory": "New Story",
+    "loading": "Loading stories…",
+    "empty": {
+      "title": "No stories yet",
+      "hint": "Create your first story to get started"
+    },
+    "row": {
+      "itemCount_one": "{{count}} item",
+      "itemCount_other": "{{count}} items",
+      "ariaLabel": "Story {{name}}, {{count}} items, {{updated}}",
+      "actionsLabel": "Actions for {{name}}"
+    },
+    "createDialog": {
+      "title": "Create New Story",
+      "description": "Create a new story to organize your voice generations into conversations.",
+      "action": "Create",
+      "creating": "Creating…"
+    },
+    "editDialog": {
+      "title": "Edit Story",
+      "description": "Update the story name and description.",
+      "saving": "Saving…"
+    },
+    "deleteDialog": {
+      "title": "Are you sure?",
+      "description": "This will permanently delete the story and all its items. This action cannot be undone.",
+      "deleting": "Deleting…"
+    },
+    "fields": {
+      "name": "Name",
+      "namePlaceholder": "My Story",
+      "descriptionLabel": "Description (optional)",
+      "descriptionPlaceholder": "A conversation between…"
+    },
+    "toast": {
+      "nameRequired": "Name required",
+      "nameRequiredDescription": "Please enter a story name",
+      "created": "Story created",
+      "createdDescription": "\"{{name}}\" has been created",
+      "createFailed": "Failed to create story",
+      "updateFailed": "Failed to update story",
+      "deleteFailed": "Failed to delete story"
+    }
+  },
+  "storyContent": {
+    "selectStory": {
+      "title": "Select a story",
+      "hint": "Choose a story from the list to view its content"
+    },
+    "loading": "Loading story…",
+    "notFound": {
+      "title": "Story not found",
+      "hint": "The selected story could not be loaded"
+    },
+    "generatingCount_one": "Generating {{count}} audio",
+    "generatingCount_other": "Generating {{count}} audios",
+    "add": "Add",
+    "searchPlaceholder": "Search by name or transcript…",
+    "searchNoMatches": "No matching generations found",
+    "searchNoAvailable": "No available generations",
+    "exportAudio": "Export Audio",
+    "empty": {
+      "title": "No items in this story",
+      "hint": "Generate speech using the box below to add items"
+    },
+    "toast": {
+      "removeFailed": "Failed to remove item",
+      "reorderFailed": "Failed to reorder items",
+      "exportFailed": "Failed to export audio",
+      "addFailed": "Failed to add generation"
+    }
+  },
   "history": {
     "deleteDialog": {
       "title": "Delete Generation",