Add Clear All button on the Ops page #1017

Summary

The Operating Room (Ops page) accumulates items across its three tabs — Needs Response, Notifications, and Resolved. Today these can only be dealt with one at a time (respond / cancel per item). Add a Clear All button so an operator can dismiss every item in the current tab in a single action.

Context

After a busy run, the Resolved tab (and Notifications) can fill up with dozens of items that no longer need attention. Clearing them individually is tedious. A single bulk action keeps the queue readable and reduces operator friction — a small UI/UX win on a page operators check frequently.

Acceptance Criteria

• A Clear All button appears in the Operating Room header/toolbar, scoped to the active tab.
• Clicking it clears all items in the current tab (e.g. cancel all pending on Needs Response, dismiss all on Resolved / Notifications).
• A confirmation step guards against accidental bulk clears.
• The button is disabled / hidden when the active tab has no items.
• Tab badge counts and the live feed update immediately after clearing (WebSocket-driven, no manual refresh needed).
• Bulk clear respects access control — only items for agents the user can access are affected.

Technical Notes

• Frontend view: src/frontend/src/views/OperatingRoom.vue (tabs: needs-response, notifications, resolved).
• Today only a per-item action exists: POST /api/operator-queue/{id}/cancel (src/backend/routers/operator_queue.py). A bulk endpoint (e.g. POST /api/operator-queue/clear with a status/agent filter) would avoid N round-trips; otherwise the frontend can iterate the per-item endpoint as a first pass.
• Operator queue statuses: pending, responded, acknowledged, expired, cancelled. Decide which the bulk action targets per tab.
• Real-time updates flow through the existing operator_queue_* WebSocket events — ensure bulk clears emit/refresh consistently.
• Stores: src/frontend/src/stores/operatorQueue.js (resolved/pending) and src/frontend/src/stores/notifications.js.