feat: make API URL configurable and improve code quality

- Add configurable API URL support via environment variables
- Update nginx configuration with environment variable substitution
- Create nginx template for dynamic proxy configuration
- Update Docker configuration for environment variable handling
- Fix hardcoded localhost:8000 references in error messages
- Add proper TypeScript types for health check API
- Format all code with Prettier for consistency
- Update documentation with configuration instructions
- Improve error messages to be environment-agnostic
- Fix duplicate imports and type safety issues

BREAKING: API URL is now configurable via VITE_API_URL (dev) and API_BACKEND_URL (prod)

frontend/eslint.config.js

@@ -1,18 +1,18 @@
-import js from '@eslint/js'
-import globals from 'globals'
-import reactHooks from 'eslint-plugin-react-hooks'
-import reactRefresh from 'eslint-plugin-react-refresh'
-import tseslint from 'typescript-eslint'
-import { globalIgnores } from 'eslint/config'
+import js from "@eslint/js";
+import globals from "globals";
+import reactHooks from "eslint-plugin-react-hooks";
+import reactRefresh from "eslint-plugin-react-refresh";
+import tseslint from "typescript-eslint";
+import { globalIgnores } from "eslint/config";
 
 export default tseslint.config([
-  globalIgnores(['dist']),
+  globalIgnores(["dist"]),
   {
-    files: ['**/*.{ts,tsx}'],
+    files: ["**/*.{ts,tsx}"],
     extends: [
       js.configs.recommended,
       tseslint.configs.recommended,
-      reactHooks.configs['recommended-latest'],
+      reactHooks.configs["recommended-latest"],
       reactRefresh.configs.vite,
     ],
     languageOptions: {
@@ -20,4 +20,4 @@ export default tseslint.config([
       globals: globals.browser,
     },
   },
-])
+]);