Integrate installation/upgrade into Dashboard Add Server dialog (#755 Phase 2)

Add Server dialog now detects the PerformanceMonitor database state after
Test Connection and offers Install Now / Upgrade options inline.

New features:
- Database status detection: no DB → Install Now, old version → Upgrade,
  current version → "up to date"
- Full installation with progress bar, scrolling log, and cancel button
- Advanced options (collapsed): clean install, reset schedule, validation,
  community dependencies
- Credential separation: post-install prompt for lower-privilege monitoring
  credentials (SQL auth only)
- Installation report generation with View Report button
- "Skip, just add server" link to bypass installation
- Edit mode skips all installation detection (existing behavior preserved)

Technical:
- Dashboard references Installer.Core, uses ScriptProvider.FromEmbeddedResources()
  (SQL scripts embedded in assembly — no filesystem dependency)
- State machine (DialogState enum) drives panel visibility
- All UI updates wrapped in Dispatcher.Invoke for thread safety
- Connection test targets master (not PerformanceMonitor) so it succeeds
  when the database doesn't exist yet
- Save button uses MinWidth+Padding to fit "Save & Connect" text

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata