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

.editorconfig

@@ -0,0 +1,60 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.{csproj,props,targets,xml,json,yml}]
+indent_style = space
+indent_size = 2
+
+[*.cs]
+indent_style = space
+indent_size = 4
+
+# See CODING_CONVENTIONS.md
+
+# Explicit types, never var
+csharp_style_var_for_built_in_types = false:warning
+csharp_style_var_when_type_is_apparent = false:warning
+csharp_style_var_elsewhere = false:warning
+dotnet_diagnostic.IDE0007.severity = none
+dotnet_diagnostic.IDE0008.severity = warning
+
+# Braces always, no single-line if
+csharp_prefer_braces = true:warning
+dotnet_diagnostic.IDE0011.severity = warning
+
+# No ternary
+dotnet_style_prefer_conditional_expression_over_assignment = false:silent
+dotnet_style_prefer_conditional_expression_over_return = false:silent
+dotnet_diagnostic.IDE0045.severity = none
+dotnet_diagnostic.IDE0046.severity = none
+
+# Usings
+dotnet_sort_system_directives_first = true
+dotnet_separate_import_directive_groups = false
+csharp_using_directive_placement = outside_namespace:warning
+dotnet_diagnostic.IDE0005.severity = warning
+
+# Namespaces
+csharp_style_namespace_declarations = file_scoped:suggestion
+
+# Allman braces
+csharp_new_line_before_open_brace = all
+csharp_new_line_before_else = true
+csharp_new_line_before_catch = true
+csharp_new_line_before_finally = true
+
+# Modifiers / this.
+dotnet_style_require_accessibility_modifiers = for_non_interface_members:suggestion
+dotnet_style_qualification_for_field = false:suggestion
+dotnet_style_qualification_for_property = false:suggestion
+dotnet_style_qualification_for_method = false:suggestion
+dotnet_style_qualification_for_event = false:suggestion
+dotnet_style_predefined_type_for_locals_parameters_members = true:suggestion
+
+# Unused
+dotnet_diagnostic.IDE0059.severity = suggestion
+dotnet_diagnostic.IDE0060.severity = suggestion