### Pre-flight Checks

• I have searched existing issues and this is not a duplicate
• I understand this issue needs status:approved before a PR can be opened

### Problem Description
Currently, the SessionsPanel only displays a static list of recent sessions. There is no way to navigate, review, or delete
specific sessions from the HUD, making it difficult for users to manage the agent's memory and "lighten" the state.

### Proposed Solution
Transform the SessionsPanel from a static display into an interactive management tool:

1. Interactive Selection: Replace static labels with a DataTable or ListView allowing single or multiple session
   selection.
2. Session Preview: Implement a preview mechanism (e.g., a side panel or tooltip) that shows a brief summary or fragments of
   the session's conversation to provide context before deletion.
3. Deletion Workflow: Add a "Delete" action that triggers a confirmation prompt before permanently removing the selected
   sessions from the agent's state.
4. Backend Integration: Implement the corresponding deletion logic in collectors/sessions.py and models.py.

### Affected Area
hermes_hud/widgets/sessions_panel.py, hermes_hud/collectors/sessions.py, hermes_hud/models.py.