Migrate menus and votes to Panorama UI Kit

Replace MenuManagerCS2 with Panorama UI Kit for the admin menus and
css_vote. Layout names (menu, vote, banner, toast) are configurable
under MenuConfig and preloaded on startup; MenuType is removed and
ConfigVersion bumped to 26.

- Drop MenuManagerApi.dll and the old chat menu classes
- Reference PanoramaUiKit.Shared.dll, bump CounterStrikeSharp to 1.0.376
- Add .editorconfig and CODING_CONVENTIONS.md, apply them codebase-wide
- Remove the CS2-SimpleAdmin-docs site
- Rewrite README for the fork

CODING_CONVENTIONS.md

@@ -0,0 +1,58 @@
+# Coding conventions
+
+Rules for all C# in this repository. `.editorconfig` enforces most of them: run
+`dotnet format CS2-SimpleAdmin.sln` before committing.
+
+## Types
+
+- Always write the explicit type. No `var`.
+  ```csharp
+  List<CCSPlayerController> players = Helper.GetValidPlayers();
+  foreach (CCSPlayerController player in players) { ... }
+  ```
+- The only exception is an anonymous type, which has no name (Dapper parameters): `var parameters = new { ... };`.
+- Target-typed `new()` and collection expressions (`[]`) are fine: the type is already written on the left.
+
+## Conditions
+
+- No ternary operator (`c ? a : b`). Write an `if`, or extract a small helper that returns.
+  ```csharp
+  string status = "OFF";
+  if (loaded)
+  {
+      status = "ON";
+  }
+  ```
+- Always use braces, even for one statement. No single-line `if (x) return;`.
+- `switch` expressions on a value are fine (`penaltyType switch { ... }`).
+- `??` and `?.` are fine.
+
+## Layout
+
+- Allman braces, 4 spaces, LF line endings.
+- File-scoped namespaces.
+- `using` directives outside the namespace, `System` first, no unused ones.
+- Early return to keep nesting shallow.
+
+## Naming
+
+- PascalCase for types, methods, properties, constants. camelCase for locals and parameters. `_camelCase` for private fields.
+- A lambda parameter you do not use is `_`. Never assign to a discard (`_ = ...`) inside a lambda whose parameter is `_`: the assignment goes to the parameter.
+
+## Duplication
+
+- When the same expression shows up in several commands, add a helper in `Helper` (see `GetCallerName`,
+  `GetReasonOrUnknown`, `GetArgsReason`, `GetAdminInfo`, `GetLogName`, `Truncate`, `HasCommandPermission`).
+
+## Comments
+
+- Comment why, not what. No commented-out code: git keeps the history.
+- XML `<summary>` on public members and on anything non-obvious.
+
+## UI
+
+- All UI goes through the Panorama UI Kit (`Menus/UiKit.cs`). Never call CounterStrikeSharp chat/center menus directly.
+- Menus are built with `MenuBuilder`. A sub-menu returns `builder.WithBackButton()`; the kit draws the back button.
+- An option closes the menu after its action, unless it passes `keepOpen: true` or its action opens another menu.
+- Panorama does not render chat color tags (`{red}`, `ChatColors`): keep them out of UI text.
+- Native calls are not thread-safe: after an `await`, come back with `Server.NextWorldUpdateAsync` before touching the UI.