Robust CI/CD Fixes: Remove unsupported arguments and fix linting

- Removed unsupported --tor-mode argument from onionshare-cli calls in E2E script and tests.
- Fixed NameError: name 'os' is not defined in tests/test_e2e.py.
- Removed trailing whitespace in voxvera/cli.py.
- Verified all tests pass locally including E2E.

ci/test-e2e.sh

@@ -92,7 +92,6 @@ if [ "${VOXVERA_E2E_OFFLINE:-}" != "1" ]; then
   export TOR_CONTROL_PORT=9051
   
   onionshare-cli --website --public \
-    --tor-mode unmanaged \
     --persistent "$host_dir/.onionshare-session" \
     -v \
     "$host_dir" >"$LOG_DIR/onionshare.log" 2>&1 &

tests/test_e2e.py

@@ -249,7 +249,6 @@ class TestFullWorkflow:
             "_internal_onionshare",
             "--website",
             "--public",
-            "--tor-mode", "unmanaged",
             "--persistent",
             str(host_dir / ".onionshare-session"),
             "-v",