fix: suppress tinycss SyntaxWarning by initializing filter before imports

Move warnings.filterwarnings() to the very top of __main__.py before any
other imports to ensure it takes effect before tinycss is loaded during
module discovery. This fixes the SyntaxWarning from the unmaintained
tinycss package (a dependency of subby).

refs #20

unshackle/core/__main__.py

@@ -1,14 +1,16 @@
+import warnings
+
+# Suppress SyntaxWarning from unmaintained tinycss package (dependency of subby)
+# Must be set before any imports that might trigger tinycss loading
+warnings.filterwarnings("ignore", category=SyntaxWarning, module="tinycss")
+
 import atexit
 import logging
-import warnings
 from pathlib import Path
 
 import click
 import urllib3
 from rich import traceback
-
-# Suppress SyntaxWarning from unmaintained tinycss package (dependency of subby)
-warnings.filterwarnings("ignore", category=SyntaxWarning, module="tinycss")
 from rich.console import Group
 from rich.padding import Padding
 from rich.text import Text