Summary

Scope model selection to the activated provider during onboarding, so users can only pick a model belonging to the provider they just enabled.

Context

During onboarding, after a user selects and activates a provider, the subsequent model-selection step previously showed models from all configured providers. This meant a user could accidentally select a model that belongs to a different (possibly unconfigured) provider, leading to confusing failures at runtime. This change tightens the flow so that immediately after a provider is activated the model list is filtered to that provider only.

Additionally, this PR simplifies the fs_patch range-calculation logic by using a detected line-ending style uniformly (removing per-line \r\n detection), removes the now-redundant out-of-bounds range error variant and its guard, and fixes a macOS Nix flake build by referencing individual Apple SDK frameworks instead of the monolithic pkgs.apple-sdk.

Changes

• Added an optional provider_filter: Option<ProviderId> parameter to select_model and on_model_selection in crates/forge_main/src/ui.rs.
• During onboarding (on_provider_activated), both the "no model set" and "current model no longer available" paths now call on_model_selection(Some(provider.id.clone())), restricting the list to the newly activated provider.
• The /model slash-command and the standalone model-selection path continue to call on_model_selection(None), preserving the current behaviour of showing all providers.
• Simplified byte-range computation in fs_patch.rs: detect line-ending style once (\r\n vs \n) and apply it uniformly, removing the per-segment \r\n detection and the RangeOutOfBounds error variant.
• Removed redundant out-of-bounds guard and the associated error tests in fs_patch.rs.
• Replaced pkgs.apple-sdk with explicit AppKit, CoreGraphics, and Foundation framework references in flake.nix.
• Removed the jobs/** entry from .gitignore.

Key Implementation Details

select_model now accepts Option<ProviderId>. When Some(id) is passed, a retain call filters all_provider_models to entries where pm.provider_id == id before the interactive selection list is built. When None is passed, the list is unchanged — exactly the existing behaviour. The change is additive and backward-compatible; all existing call-sites pass None except the two onboarding paths that now pass the activated provider's id.

Testing

# Verify the codebase compiles cleanly
cargo check

# Run all tests (snapshot tests are accepted automatically)
cargo insta test --accept

To exercise the onboarding flow manually:

1. Start the CLI with no model configured.
2. Run /provider and activate a provider (e.g. Anthropic).
3. Confirm that the subsequent model picker only lists models for Anthropic.
4. Run /model from the main prompt and confirm all providers are shown as before.