chore(client/ts): port services/mermaid

src/public/app/services/mermaid.ts

@@ -11,7 +11,7 @@ let elkLoaded = false;
  * 
  * @param mermaidContent the plain text of the mermaid diagram, potentially including a frontmatter.
  */
-export async function loadElkIfNeeded(mermaidContent) {
+export async function loadElkIfNeeded(mermaidContent: string) {
     if (elkLoaded) {
         // Exit immediately since the ELK library is already loaded.
         return;

src/public/app/types.d.ts

@@ -128,8 +128,20 @@ declare global {
             securityLevel: "antiscript"
         }): void;
         render(selector: string, data: string);
+    }
+    interface MermaidLoader {
+
     }
     var mermaid: {        
         mermaidAPI: MermaidApi;
-    };
+        registerLayoutLoaders(loader: MermaidLoader);
+        parse(content: string, opts: {
+            suppressErrors: true
+        }): {
+            config: {
+                layout: string;
+            }            
+        }
+    };
+    var MERMAID_ELK: MermaidLoader;
 }