Update the mock API to alphabetize paginated list queries

[charliepark]

The API will automatically sort items by name ascending if no sort_by query param is included to override that. We should update the paginated helper in the mock API to match this behavior. [Investigate this to verify, but it's likely correct.]

• default name or ID sort mode is name ascending
• instance list paginates by name or id

(From a PR)

[charliepark]

Just following up with Claude's analysis of Omicron:

Default Sorting Behavior

For endpoints that support sorting by name or ID (most common case - like projects, instances, disks, etc.):

• Default: name_ascending (line 427-428 in common/src/api/external/http_pagination.rs)
• Items are sorted alphabetically by name in ascending order

For endpoints that only support sorting by ID:

• Default: id_ascending (line 334-335)
• Items are sorted by UUID in ascending order

For endpoints that sort by timestamp and ID (like audit logs):

• Default: time_and_id_ascending (line 511-512)
• Items are sorted by timestamp (oldest first), then by ID

How it works

The code uses Serde's #[serde(default = "...")] attribute on the sort_by field. When you don't provide a sort_by query parameter, it automatically applies the default:

fn default_nameid_sort_mode() -> NameOrIdSortMode {
    NameOrIdSortMode::NameAscending  // Most common default
}

So if you call GET /v1/projects without any sort_by parameter, you'll get results sorted by project name in alphabetical order (A-Z) by default.