Bump version 1.8.0 -> 1.9.0 for release (#293)

Highlights since v1.8.0:
- Minimap for plan navigation (#276)
- Colored links by accuracy ratio divergence (#289)
- Distinct parallelism subtype icons (#285, #288)
- Query Store filter ordering fix (#287)
- xunit v2 -> v3 migration (#278)
- SqlClient 6 -> 7, ScriptDom 170 -> 180 (#279)
- System.CommandLine GA (#280)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata

src/PlanViewer.App/PlanViewer.App.csproj

@@ -6,7 +6,7 @@
     <ApplicationManifest>app.manifest</ApplicationManifest>
     <ApplicationIcon>EDD.ico</ApplicationIcon>
     <AvaloniaUseCompiledBindingsByDefault>true</AvaloniaUseCompiledBindingsByDefault>
-    <Version>1.8.0</Version>
+    <Version>1.9.0</Version>
     <Authors>Erik Darling</Authors>
     <Company>Darling Data LLC</Company>
     <Product>Performance Studio</Product>