Improve exception reporting in geocoding error handlers

[Copilot]

The geocoding click handlers caught generic exceptions but only displayed ex.Message, losing stack traces and exception types needed for debugging.

Changes

• Exception display: Changed from {ex.Message} to {ex} in markdown code blocks to show full exception details (type, message, stack trace)
• Applied to: RiskMapLayoutArea.cs and PropertyRisksLayoutArea.cs
• Type inference fix: Changed .Select() to .SelectMany() in RiskMapLayoutArea.cs where lambda returns were mixing UiControl and IObservable<UiControl>

// Before
catch (Exception ex)
{
    obj.Host.UpdateArea(obj.Area, Controls.Markdown($"**Geocoding Failed**: {ex.Message}"));
}

// After
catch (Exception ex)
{
    obj.Host.UpdateArea(obj.Area, Controls.Markdown($"**Geocoding Failed**:\n```\n{ex}\n```"));
}

Follows the pattern established in DomainViews.cs for error display.

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