fix: version badge rendering, Jinja2 scoping, navbar i18n, missing GET task endpoint

- Fix version badge showing [object Object] or Python dict dump in
  select_recipe, task_list, and task_complete templates by accessing
  current_version.version_number instead of the whole object
- Fix recipe_editor.html Internal Server Error caused by Jinja2 block
  scoping: {% set %} variables from block content were invisible in
  block extra_js, replaced with direct recipe.* references
- Fix task_editor.html SyntaxError from Italian apostrophe in
  nell'eliminazione breaking JS string literals, switched to |tojson
- Add i18n {{ _() }} wrappers to all hardcoded navbar strings (desktop
  and mobile menus) so language toggle works correctly
- Add app title text "TieMeasureFlow" next to logo in navbar
- Add missing GET /api/tasks/{task_id} endpoint on server that caused
  405 Method Not Allowed when starting measurements

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

server/routers/tasks.py

@@ -112,6 +112,17 @@ async def list_tasks(
     return [TaskResponse.model_validate(t) for t in tasks]
 
 
+@router.get("/api/tasks/{task_id}", response_model=TaskResponse)
+async def get_task(
+    task_id: int,
+    _user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Get a single task with its subtasks. All authenticated users."""
+    task = await _get_task_or_404(db, task_id)
+    return TaskResponse.model_validate(task)
+
+
 @router.post(
     "/api/recipes/{recipe_id}/tasks",
     response_model=TaskResponse,