@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
@

src/GmRelay.Web/Components/Layout/NavMenu.razor

@@ -82,7 +82,7 @@
                     </button>
                 </form>
 
-                <div class="nav-version">v3.7.1</div>
+                <div class="nav-version">v3.8.0</div>
             </div>
         </Authorized>
         <NotAuthorized>