Update environment variable loading to support process environment and improve error handling

Co-authored-by: Copilot <copilot@github.com>

twitch-archive.py

@@ -137,7 +137,7 @@ class TwitchArchive:
     
     def _load_environment_variables(self) -> None:
         """
-        Load environment variables from .env file.
+        Load environment variables from process environment or an optional .env file.
         
         Required variables:
         - CLIENT-ID: Twitch API client ID
@@ -148,16 +148,26 @@ class TwitchArchive:
         - PASSWD: Email password for sending notifications (if enabled)
         
         Raises:
-            SystemExit: If .env file is not found
+            SystemExit: If required Twitch API credentials are unavailable
         """
+        has_required_env = bool(
+            get_env_value('CLIENT-ID', 'CLIENT_ID') and
+            get_env_value('CLIENT-SECRET', 'CLIENT_SECRET')
+        )
+
+        if has_required_env:
+            print(f'{Fore.GREEN}✓ Twitch API credentials loaded from process environment{Style.RESET_ALL}')
+            return
+
         dotenv_loaded = load_dotenv(find_dotenv())
         has_required_env = bool(
             get_env_value('CLIENT-ID', 'CLIENT_ID') and
             get_env_value('CLIENT-SECRET', 'CLIENT_SECRET')
         )
 
-        if not dotenv_loaded and has_required_env:
-            print(f'{Fore.GREEN}✓ Twitch API credentials loaded from process environment{Style.RESET_ALL}')
+        if has_required_env:
+            if dotenv_loaded:
+                print(f'{Fore.GREEN}✓ Twitch API credentials loaded from .env file{Style.RESET_ALL}')
             return
 
         if not dotenv_loaded and not has_required_env: