Render saved settings immediately

[Hanjo92]

Summary

• Render the settings panel from the normalized submitted configuration immediately after save.
• Remove the API-key gate that prevented hosted provider/model/base URL settings from being saved when the key field was blank.
• Send the saved configuration back to the currently visible webview and update the DOM immediately, so the status does not stay stuck on Saving.
• Keep runtime provider clients responsible for surfacing missing API key errors when the provider is actually used.
• Add regression coverage for delayed VS Code configuration propagation, hosted-provider saves without keys, and visible webview updates after save.
• Bump the installable package to 0.0.7.

Verification

• npm run check
• npm run package

Fixes #25
Fixes #27
Fixes #28