GeezerVison

Closes #702

A custom view can be saved as the default view for individual users. TSC has no way to list those users or to set them. This adds both.

New methods

• server.custom_views.get_users_with_default(view, req_options=None) returns (list[UserItem], PaginationItem): the users who have this custom view as their default. Paginated.
• server.custom_views.set_as_default_for_users(view, users, strict=False) sets the custom view as the default for up to 100 users and returns a list[UserDefaultViewAssignment] with user_id, success, error_code and summary for each user.

Both are API 3.21+ and administrator-only. Both accept a CustomViewItem or an ID; users accepts UserItems or IDs.

This is separate from WorkbookItem.default_view_id, which is one value per workbook shared by every user.

Behavior to review

• The server applies each user independently, so a call can partly succeed. By default the per-user outcome is returned and failures are logged. With strict=True, DefaultViewAssignmentError is raised after the request when any user failed; .failures holds those results. Users that succeeded are still updated, so strict mode is not all-or-nothing.
• Client-side validation raises before any request: MissingRequiredFieldError for a missing view ID, TypeError if users is a single string, ValueError for no users, more than 100, or a user without an ID.
• Success_codes is now any 2xx (range(200, 300)). The REST docs list 200 for the set call, but Tableau Server's implementation responds 207 Multi-Status, which TSC rejected. This is global: 207 is not used by any other endpoint, and no in-repo code or test relies on a 2xx being treated as an error. The one behavior change is that a 205 or 206 response carrying an error body would now parse as success; no endpoint TSC calls returns those.
• The test fixtures are built from the REST API docs and the response schema, not captured from a live server.

Written with Claude Code