Add tag overview, improve assets

CHDataManagement/Generator/HeaderElement.swift

@@ -0,0 +1,33 @@
+
+enum HeaderElement {
+    case css(FileResource)
+    case js(file: FileResource, defer: Bool)
+    case jsModule(FileResource)
+    case title(String)
+    case description(String)
+    case charset
+    case viewport
+}
+
+extension HeaderElement {
+
+    var content: String {
+        switch self {
+        case .css(let file):
+            return "<link rel='stylesheet' href='\(file.assetUrl)' />"
+        case .js(let file, let deferred):
+            let deferText = deferred ? " defer" : ""
+            return "<script src='\(file.assetUrl)'\(deferText)></script>"
+        case .jsModule(let file):
+            return "<script type='module' src='\(file.assetUrl)'></script>"
+        case .title(let title):
+            return "<title>\(title)</title>"
+        case .description(let description):
+            return "<meta name='description' content='\(description)'>"
+        case .charset:
+            return "<meta charset='utf-8' />"
+        case .viewport:
+            return "<meta name='viewport' content='width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1' />"
+        }
+    }
+}