@chore(release): bump version to 3.8.0 (issue #111)

Game-creation wizard: replace /newsession text template with step-by-step
inline-keyboard flow for single games and game pools.

- Directory.Build.props: 3.7.1 -> 3.8.0
- compose.yaml: pin bot, discord-bot and web images to 3.8.0
- deploy.yml VERSION env: 3.7.1 -> 3.8.0
- NavMenu.razor: nav-version 3.7.1 -> 3.8.0

🤖 Generated with Claude Code
@

Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <Version>3.7.1</Version>
+    <Version>3.8.0</Version>
     <TargetFramework>net10.0</TargetFramework>
     <LangVersion>preview</LangVersion>
     <Nullable>enable</Nullable>