Deprecate `useAppConfig` → `getAppConfig`

[aklinker1]

Feature Request

Follow up to #1911 to deprecate the old function in v1.0.

Is your feature request related to a bug?

• Rename useAppConfig to getAppConfig to avoid linter complaints/ai confusion #1911
• fix: Add getAppConfig as an alias to useAppConfig #2144

What are the alternatives?

N/A

Additional context

N/A