Move collect.py into server/; split main() into server/main.py

run() stays in server/collect.py with relative imports.
main() (CLI arg parsing, credential loading) moves to server/main.py.
install.sh updated to use `python -m server.main` (required for relative
imports to resolve correctly when invoked as a module).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

install.sh

@@ -100,7 +100,7 @@ Wants=network-online.target
 [Service]
 Type=simple
 WorkingDirectory=$SCRIPT_DIR
-ExecStart=$PYTHON $SCRIPT_DIR/collect.py -c $CREDS_FILE
+ExecStart=$PYTHON -m server.main -c $CREDS_FILE
 Restart=on-failure
 RestartSec=60
 StandardOutput=journal