Improve endpoint model setup UX

[FuJacob]

Summary

Simplify Local Endpoint setup by keeping one always-visible model control, automatically selecting a stable discovered model, and presenting the API format explicitly. Fix the underlying state bug where choosing a model or API format cleared the discovered catalog and reset the connection to Not connected.

The settings UI also removes duplicate SwiftUI field labels, keeps manual model entry available, shows compact inline connection feedback, and updates settings-search terminology.

Validation

• xcodebuild -project Cotabby.xcodeproj -scheme Cotabby -destination platform=macOS test -derivedDataPath build/DerivedData CODE_SIGNING_ALLOWED=NO
  • TEST SUCCEEDED — 1,688 tests, 7 skipped, 0 failures
• xcodebuild -project Cotabby.xcodeproj -scheme Cotabby -destination platform=macOS build-for-testing -derivedDataPath build/DerivedData CODE_SIGNING_ALLOWED=NO
  • TEST BUILD SUCCEEDED
• swiftlint --strict
  • 0 violations in 249 files

Linked issues

No linked issue.

Risk / rollout notes

When discovery returns models and the saved selection is missing or stale, Cotabby now chooses the alphabetically first discovered model. A manual identifier is preserved when the endpoint returns an empty catalog. No settings migration is required.

Greptile Summary

This PR improves the OpenAI-compatible endpoint setup flow. The main changes are:

• Keeps the endpoint catalog connected while model and API format change.
• Adds a resolver for choosing a discovered model after refresh.
• Reworks the settings pane into one manual model field with a discovered-model menu.
• Renames endpoint settings search text around Server URL and API Format.
• Adds tests for model selection resolver behavior.

Confidence Score: 4/5

The endpoint setup flow has one persisted-model selection bug to fix before merging.

• A non-empty manual model can be replaced by the first discovered model after refresh.
• The UI refactor and connection-state changes otherwise keep the same settings bindings and request-time configuration flow.
• No security issue was found in the changed code.

Cotabby/Models/OpenAICompatibleEndpointModels.swift

Important Files Changed

Filename	Overview
Cotabby/App/Core/CotabbyAppEnvironment.swift	Stops invalidating endpoint discovery for model and API-format edits; generation still reads current settings at request time.
Cotabby/Models/OpenAICompatibleEndpointModels.swift	Adds model selection reconciliation, but the fallback can overwrite manual model IDs that are absent from a non-empty catalog.
Cotabby/UI/Settings/Panes/EngineAndModelPaneView.swift	Refactors endpoint settings UI and persists resolver output after refresh.
Cotabby/UI/Settings/SettingsIndex.swift	Updates endpoint settings labels, descriptions, and search keywords.
CotabbyTests/OpenAICompatibleAPIClientTests.swift	Adds resolver tests for empty, preserved, stale, and empty-catalog selections.

_{Reviews (1): Last reviewed commit: "Improve endpoint model setup UX" | Re-trigger Greptile}

Greptile also left 1 inline comment on this PR.

[greptile-apps]

Manual Model Gets Overwritten

When a user has a non-empty manual model that is not returned by /models, this fallback returns the first discovered model and refreshEndpointModels() persists it. Servers can return a filtered catalog while still accepting hidden model IDs, so opening the pane or pressing Refresh can silently move future completions to a different model.

Suggested change

	return firstModel.id
	return current.isEmpty ? firstModel.id : nil