fix(useController): preserve values when shouldUnregister changes - #13996

Proposed Changes

Changing the field-level shouldUnregister option reruns the registration effect and cleans up an input that is still mounted. For example, changing true to false removes its edited value from getValues().

Track the committed option independently of registration. Update default-value initialization when the option changes, while keeping registration and cleanup tied to field identity. This preserves inline defaults after reset() and the previous field policy when name or control changes. Form-level precedence and the field-array action guard stay unchanged. This complements #13956 for the field-level option.

Add 12 cases covering option transitions, form-level overrides, identity changes, and inline defaults. Four mounted-option cases fail against the original implementation.

Validation with Node 22:

• 133 suites, 1,844 unit tests and 26 snapshots passed.
• All 90 existing Chromium E2E tests passed with one worker and no retries, using a local browser/server configuration. Test files and assertions are unchanged.
• pnpm type, pnpm test:type, lint, Prettier, builds, and both API Extractor checks passed. No added lint warnings; the API report is unchanged.

Type of change

• Bug fix

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes