[goroyabu]

Summary

• remove the empty optional title value from the maintenance proposal Issue Form
• allow GitHub schema validation to accept and render the form

Related Issue

None. This is a narrow correction to the Issue template itself.

Verification

• reproduced the failure with a semantic check that rejects an empty optional title
• confirmed the same check succeeds after removing the key
• parsed both Issue Form YAML files and confirmed their required top-level keys are present and no top-level string is empty
• git diff --check completed without errors
• build and CTest were not run because this change affects only GitHub Issue Form metadata

Impact

The maintenance proposal form can be rendered and used again. Build, runtime, installation, package, CI, and release behavior are unchanged.

Documentation

No user documentation changes are needed.

Checklist

• The change is focused on one coherent maintenance correction.
• Relevant verification has been run and reported above.
• No build outputs, generated files, or local configuration were committed.