feat(discord): make /newsession identical to Telegram wizard

- Remove legacy DiscordNewSessionCommand/Handler and their tests.
- Rename /newsession-wizard to /newsession.
- Add shared pool capacity step before Format/Location.
- Render Format and Location in Discord wizard; Location uses a modal.
- Propagate Format, JoinLink and LocationAddress in BuildCommand.
- Publish created sessions through existing IPlatformMessenger pipeline.
- Update README, version bump to 3.11.1, sync compose/deploy/NavMenu.

Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <Version>3.11.0</Version>
+    <Version>3.11.1</Version>
     <TargetFramework>net10.0</TargetFramework>
     <LangVersion>preview</LangVersion>
     <Nullable>enable</Nullable>