refactor: share env-bool parsing and logging setup

env_utils.env_bool replaces duplicated truthy parsing in config and
rembg_cli. logging_config.configure_logging unifies entry-point setup.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/env_utils.py

@@ -0,0 +1,12 @@
+"""Shared environment-variable parsing."""
+
+from __future__ import annotations
+
+import os
+
+
+def env_bool(name: str, default: bool) -> bool:
+    raw = os.environ.get(name)
+    if raw is None:
+        return default
+    return raw.strip().lower() in {"1", "true", "yes", "on"}