refactor(environment): rename config keys to camelCase

Aligns environment.* shape with TypeScript convention.
Renames: api_url -> apiBaseUrl, api_key -> apiKey,
use_api_key -> useApiKey, refresh_interval -> refreshInterval,
google_map_api_key -> googleMapApiKey.

The local environment.{ts,development.ts,local.ts} files are
gitignored and have already been migrated; this commit updates
the tracked example file and the only consumer (apiInterceptor).

src/app/core/interceptors/api.interceptor.ts

@@ -7,7 +7,7 @@ export const apiInterceptor: HttpInterceptorFn = (req, next) => {
         setHeaders: {
             ...({ 'Content-Type': 'application/json', 'Accept': 'application/json' }),
         },
-        url: `${environment.api_url}${req.url}`
+        url: `${environment.apiBaseUrl}${req.url}`
     });
     return next(apiReq);
 };

src/environments/environment.example.ts

@@ -1,8 +1,14 @@
 export const environment = {
+    // Used by build system to enable dev mode optimizations
     production: <boolean> false,
-    api_url:<string> 'http://localhost:3200/api',
-    api_key:<string> '<YOU-API-KEY-HERE>',
-    use_api_key:<boolean> true,
-    refresh_interval:<number> 30000,
-    google_map_api_key:<string> '<YOUR-GOOGLE-MAP-API-KEY-HERE>'
+    // Note: Currently used via apiInterceptor. Deprecated: duplicate of apiUrl, consider removing
+    apiBaseUrl: <string> 'http://localhost:3200/api',
+    // Reserved for API key-based authentication (not currently used, see useApiKey)
+    apiKey: <string> '<YOU-API-KEY-HERE>',
+    // Reserved for toggling between JWT and API key authentication (not currently used)
+    useApiKey: <boolean> true,
+    // Reserved for data polling/refresh intervals (not currently used)
+    refreshInterval: <number> 30000,
+    // Reserved for Google Maps API integration (not currently used)
+    googleMapApiKey: <string> '<YOUR-GOOGLE-MAP-API-KEY-HERE>'
 };