feat(rest-api): expose active task summaries on racks and trays

[kunzhao-nv]

Problem

Rack and tray REST responses expose current inventory state but do not indicate whether an operation is already active for the resource. Clients must issue a separate task-list request for every resource, which creates extra requests and can observe a different snapshot.

Proposed API contract

Add the following required field to both rack and tray detail/list response items:

"taskSummary": {
  "activeTaskIds": ["<task UUID>"]
}

• activeTaskIds contains tasks in Waiting, Pending, or Running state.
• The array is always present and is empty when no task is active.
• IDs are ordered deterministically by task creation time and then task ID.
• A rack summary includes every active task on the rack, including component-scoped tasks.
• A tray summary includes only active tasks that explicitly target that tray.
• The active count is intentionally not stored separately because clients can derive it from activeTaskIds; this avoids two representations of the same state drifting apart.

Implementation notes

• Fetch summaries in one Flow-side batch per inventory response; do not add per-rack or per-tray REST calls.
• Update both detail and list APIs, the OpenAPI source, generated SDK/reference artifacts, and handler/model tests.
• Keep historical/terminal task IDs out of inventory responses; clients can use the existing task-list endpoints for history.

Acceptance criteria

• Rack and tray detail/list responses return taskSummary.activeTaskIds.
• Active status, rack/tray targeting, empty-array behavior, and deterministic ordering are covered by tests.
• The public OpenAPI contract and generated artifacts are in sync.