Describe the bug
Setup prints misleading config error and logs unclosed aiohttp session

To Reproduce
Steps to reproduce the behavior:

1. Ensure data dir exists but config.json does not.
2. Run iSponsorBlockTV setup.
3. Exit setup after creating config.
4. Actual output:

Could not load config file
Blank config file created
After exit: asyncio - ERROR - Unclosed client session ...

To be clear, the config is properly generated.

Expected behavior

• No error message for normal first-run config creation.
• No asyncio “Unclosed client session” error on setup exit.

Environment

iSponsorBlockTV installed and run via systemd (data dir exists, e.g. /var/lib/isponsorblocktv)
Command: iSponsorBlockTV setup

Additional context

• Config.__load() prints error text for the expected first-run FileNotFoundError and prints “Blank config file created” even though it doesn’t create a file (see src/iSponsorBlockTV/helpers.py (line 82) and src/iSponsorBlockTV/helpers.py (line 104)). This is misleading when the data dir already exists.
• aiohttp.ClientSession instances created during setup are never closed, leading to the asyncio error:
  • Setup wizard: AddDevice and AddChannel (src/iSponsorBlockTV/setup_wizard.py (line 234), src/iSponsorBlockTV/setup_wizard.py (line 387))
  • CLI setup: src/iSponsorBlockTV/config_setup.main() (src/iSponsorBlockTV/config_setup.py (line 83))