Make report panel auto-refresh with latest scan results

[dollfins]

Description

The report panel (reportPanel.ts) is a static snapshot. Once opened, it does not update when new scan results arrive. Users must close and re-open the panel to see fresh results. The status bar shows the latest score, but the report panel falls out of sync.

Current Behavior

• showReportPanel() creates a new webview each time
• The caller passes diagnosticsProvider.lastReport which is a snapshot
• No mechanism exists to push updates to an already-open panel

Expected Behavior

Option A: Auto-refresh open panel

• Track if a report panel is currently open
• When new scan results arrive, post a message to the webview with updated data
• The webview re-renders findings and score in-place

Option B: Reveal existing panel

• Before creating a new panel, check if one already exists
• If it does, reveal it (bring to front) instead of creating a duplicate
• Optionally refresh its content

Recommended: Both

• Reuse the existing panel if one is open
• Auto-refresh content when new scan results are available
• Use panel.webview.postMessage({ type: 'update', results }) to push updates

Implementation Notes

• Store the active panel reference in a module-level variable
• Register a postMessage handler in the webview JS
• In diagnostics.ts, after scan completes, call a updateReport() function
• Handle the case where the panel has been closed by the user (dispose event)

Acceptance Criteria

• Report panel is reused (not duplicated) when reopened
• Panel content refreshes automatically after a new scan
• Closing and reopening the panel works correctly
• The panel title shows the scan timestamp or score
• No memory leaks (panel disposal is handled)

Complexity

Medium — requires webview lifecycle management and cross-module communication.

Points

150