[Bug]: Desktop/TUI session.resume fails with "No LLM provider configured" when session only stored a bare billing

#44022 Fixed P2 comp/gateway

[Bug]: Desktop/TUI session.resume fails with "No LLM provider configured" when session only stored a bare billing_provider (e.g. custom)

Resuming any older chat in the Hermes desktop or TUI app fails with "No LLM provider configured" even though the default provider is valid and new chats work fine, while the identical session resumes correctly via the CLI's --resume flag.