Make helper scripts directly executable with uv run shebang

guibuild.py and release.py use the project environment; rtorrent-manager.py
is standalone and declares its own dependency via uv script metadata.

scripts/guibuild.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env -S uv run
 """Build the desktop GUI application and package it as a version-numbered ZIP.
 
 Usage:

scripts/release.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env -S uv run
 """Publish a MediaHive release to Gitea.
 
 Usage:

scripts/rtorrent-manager.py

@@ -1,4 +1,10 @@
-#!/usr/bin/env python3
+#!/usr/bin/env -S uv run
+# /// script
+# requires-python = ">=3.14"
+# dependencies = [
+#     "bencodepy>=0.9.5",
+# ]
+# ///
 """Torrent Scanner - Scans for .torrent files and analyzes their trackers."""
 
 import argparse