Lite: Tooltips use default Windows light theme instead of dark mode

[erikdarlingdata]

Description

Tooltips throughout Lite use plain strings or default WPF tooltip styling, which renders them with a light/white background that clashes with the dark theme.

Affected Areas

Code-behind (dynamic tooltips):

• MainWindow.xaml.cs — Collector health tooltips (lines 340, 347)
• MainWindow.xaml.cs — Alert badge tooltip (line 652) — fixed in feature/loading-empty-states

XAML (static/bound tooltips):

• ServerTab.xaml — ComboBox tooltips ("Hour", "Minute", "Apply to All")
• ServerTab.xaml — DataGrid cell tooltips bound to QueryText, BlockedSqlText, BlockingSqlText, SqlText (~6 instances)
• SettingsWindow.xaml — Email field tooltip
• AddServerDialog.xaml — Azure auth tooltips (~3 instances)
• MainWindow.xaml — Sidebar toggle tooltip

Fix

Either:

1. Add a global dark ToolTip style to DarkTheme.xaml (simplest, catches everything)
2. Or individually style each tooltip

Option 1 is strongly preferred — a single implicit style for ToolTip would fix all current and future tooltips.