# Tool Session Progress Indication and Live Updates

## Why

Creating or deleting a tool session currently leaves the UI out of sync. After starting a tool from the floating action button, the new session does not appear on `/sessions` or the dashboard until the user manually refreshes or the 30-second poll fires. The existing progress feedback is also poor: `CreateSessionForm` shows a blocking overlay with only two static messages ("Creating instance…", "Starting container…"), and `SessionCard`/`InstanceCard` dim the whole card with a generic spinner. Users cannot see real backend progress (building, starting, probing, running, error) and receive no confirmation when an action finishes.

## What Changes

- Introduce a **global session progress panel** that tracks all lifecycle actions (create, start, stop, restart, delete, recreate tunnel) using the existing SSE event stream (`instance.created`, `instance.started`, `instance.health_changed`, `instance.error`, `instance.stopped`, `instance.deleted`, `instance.restarted`).
- Make lists update **immediately** after create/delete by sharing session state across `AppShell`, `DashboardPage`, and `SessionsPage`.
- Remove the blocking full-screen overlay in `CreateSessionForm` and the card-level busy overlays; replace them with minimal disabled/spinner states and the global panel.
- Keep existing toast notifications for terminal states (success/error) while the panel handles in-flight progress.

## Capabilities

### New Capabilities
- `session-progress-panel`: Global, non-blocking progress UI for tool lifecycle actions driven by SSE events.
- `shared-session-state`: Centralized session list used by navigation, dashboard, and sessions page.

### Modified Capabilities
- `session-lifecycle-ux`: Delete and stop actions now update shared state immediately; create/start actions add a pending session and show progress.
- `sessions-hub`: Dashboard and sessions lists reflect new/deleted sessions without manual refresh.

## Impact

- Frontend: new `state/session-operations.tsx`, new `components/features/session/session-progress-panel.tsx`, updates to `state/sessions.tsx`, `AppShell`, `SessionsPage`, `DashboardPage`, `hooks/use-instance-actions.ts`, `components/features/tool/instance-list.tsx`, `components/features/tool/tool-starter.tsx`, `components/features/session/create-session-form.tsx`, `components/features/session/session-card.tsx`, and styles.
- No API changes: relies on existing lifecycle events and `/users/me/sessions`.

## Quality Gates

- `npm run typecheck`
- `npm run lint`
- Existing frontend tests still pass
- Manual verification: create and delete sessions from the FAB and repository detail page; verify panel updates and lists refresh without manual reload.
