Add collector health detail view to Lite UI

[erikdarlingdata]

Problem

When collectors are failing, the Lite status bar shows a count ("Collectors: 1 erroring") with a tooltip containing the failing collector names and error messages. But this tooltip is easy to miss and hard to read for multiple failures.

The backend infrastructure already exists:

• collection_log DuckDB table stores every collector run with status, error messages, and timing
• LocalDataService.GetCollectionHealthAsync() computes per-collector health status (HEALTHY / WARNING / STALE / FAILING / NEVER_RUN), failure rates, and average durations
• CollectorHealthRow model has all the fields needed for display

But nothing in the UI calls GetCollectionHealthAsync() — the data is collected and computed but never shown.

Proposed Solution

Add a "Collection Health" tab or panel in the ServerTab that displays a DataGrid with:

Column	Source
Collector	CollectorName
Status	HealthStatus (color-coded)
Total Runs	TotalRuns
Success / Error	SuccessCount / ErrorCount
Failure Rate	FailureRatePercent
Avg Duration	AvgDurationFormatted
Last Success	LastSuccessTime
Last Error	LastError (truncated, tooltip for full message)

This would make it immediately obvious which collectors are healthy and which need attention, without hovering over a status bar tooltip.

Related Files

• Lite/Services/LocalDataService.CollectionHealth.cs — GetCollectionHealthAsync() (line 21), CollectorHealthRow model (line 66)
• Lite/Services/RemoteCollectorService.cs — CollectorHealthEntry (line 32), RecordCollectorResult() (line 156)
• Lite/MainWindow.xaml.cs — UpdateCollectorHealth() (line 287) — current tooltip-only display
• Lite/Database/Schema.cs — collection_log table schema (line 37)

[erikdarlingdata]

Implemented in PR #42.