Merge branch 'V2' into V2-eslint-no-undef

# Description of Changes
There's no current linter running over our TypeScript code, which means
we've got a bunch of dead code and other code smells around with nothing
notifying us. This PR adds ESLint with the typescript-eslint plugin and
enables the recommended settings as a starting point for us.

I've disabled all of the failing rules for the scope of this PR, just to
get linting running without causing a massive diff. I'll follow up with
future PRs that enable the failing rules one by one.

Also updates our version of TypeScript, which introduces a new type
error in the code (which I've had to fix)

frontend/eslint.config.mjs

@@ -9,13 +9,13 @@ export default defineConfig(
   eslint.configs.recommended,
   tseslint.configs.recommended,
   {
-    "ignores": [
+    ignores: [
       "dist", // Contains 3rd party code
       "public", // Contains 3rd party code
     ],
   },
   {
-    "rules": {
+    rules: {
       "no-empty": "off", // Temporarily disabled until codebase conformant
       "no-empty-pattern": "off", // Temporarily disabled until codebase conformant
       "no-useless-escape": "off", // Temporarily disabled until codebase conformant
@@ -37,8 +37,8 @@ export default defineConfig(
     languageOptions: {
       globals: {
         ...globals.browser,
-      }
-    }
+      },
+    },
   },
   // Config for node scripts
   {
@@ -50,7 +50,7 @@ export default defineConfig(
     languageOptions: {
       globals: {
         ...globals.node,
-      }
-    }
+      },
+    },
   },
 );