refactor: update findAppRoot function and adjust Dockerfile paths for consistency

app/backend/src/template-service.ts

@@ -3,7 +3,7 @@ import { join } from "node:path";
 import nunjucks from "nunjucks";
 import type { ImageSelection, UsageTemplate } from "./types";
 
-const findAppNewRoot = (): string => {
+const findAppRoot = (): string => {
   const candidates = [join(__dirname, "../../.."), join(__dirname, "../..")];
 
   for (const candidate of candidates) {
@@ -12,19 +12,19 @@ const findAppNewRoot = (): string => {
     }
   }
 
-  throw new Error("Unable to resolve app-new template root");
+  throw new Error("Unable to resolve app template root");
 };
 
 export class TemplateService {
-  private readonly appNewRoot = findAppNewRoot();
+  private readonly appRoot = findAppRoot();
 
-  private readonly env = nunjucks.configure(join(this.appNewRoot, "templates"), {
+  private readonly env = nunjucks.configure(join(this.appRoot, "templates"), {
     autoescape: false,
     noCache: true
   });
 
   private readonly templates: UsageTemplate[] = JSON.parse(
-    readFileSync(join(this.appNewRoot, "templates.json"), "utf8")
+    readFileSync(join(this.appRoot, "templates.json"), "utf8")
   ) as UsageTemplate[];
 
   public getTemplates(): UsageTemplate[] {