v0.8.2

Phosphor v0.8.2

This release lets local-model users configure a custom provider directly
during first-run onboarding, instead of only through the ctrl+p command
menu after setup.

Custom provider setup during onboarding

The first-run model picker now offers a "custom provider" entry that opens
a setup wizard. It collects:

• provider id (validated, no silent clobbering of existing providers)
• base URL
• API key (optional — e.g. for local endpoints that don't require one)
• model ids
• context window size (optional)
• attachment/image support (yes/no)

On finish, the provider is written to the global config and onboarding
auto-selects its first model, so summarization and image paste work
immediately without a second trip through the model picker.

Note: leaving the context window unset (0) disables auto-summarization for
that model — set it for endpoints you plan to summarize against.