feat(ui/design): Monaco editor for script code fields

Vendors Monaco 0.55.1 min/vs/ (~15 MB) at
wwwroot/lib/monaco/vs/. No CDN dependency; works on air-gapped
deployments. Loaded lazily on first script-edit via the AMD loader.

wwwroot/js/monaco-init.js exposes window.MonacoBlazor with
createEditor / setValue / getValue / setMarkers / dispose. Handles
loader bootstrap, DotNet round-trip on content change, and marker
sets for later diagnostic wiring.

Components/Shared/MonacoEditor.razor is a Blazor wrapper with
Value / ValueChanged / Language / Height / ReadOnly parameters and
IAsyncDisposable teardown. Bidirectional binding tracks
_lastSentValue to avoid push/pull loops.

Replaces the plain textareas in SharedScriptForm, TemplateEdit's
Add-Script form, and ApiMethodForm. Default height 320px ≈ the
previous rows=10. Build / tests / dialog flow unaffected.

Wave 1 of three. Roslyn-backed completions and SCADA-specific
extensions follow in subsequent commits.

src/ScadaLink.CentralUI/wwwroot/lib/monaco/vs/language/css/monaco.contribution.js

@@ -0,0 +1 @@
+define("vs/language/css/monaco.contribution",["exports","../../editor.api-CalNCsUg","../../monaco.contribution-DO3azKX8"],(function(s,t,e){"use strict";s.cssDefaults=e.cssDefaults,s.lessDefaults=e.lessDefaults,s.scssDefaults=e.scssDefaults,Object.defineProperty(s,Symbol.toStringTag,{value:"Module"})}));