Unify native resizable project fields

[Zephyr-Song]

What changed

• Standardized Project title, Research area and ethics-review context, Project plan, and People and relationships as matching multiline fields.
• Reused the original native resizable textarea style from Project plan and People and relationships for all four fields.
• Kept vertical drag-to-resize behavior without a field-specific fixed or maximum height.
• Normalized line breaks in saved project titles to spaces.
• Added regression coverage for the unified markup and native resizing behavior.

Why

The four core project fields looked inconsistent. Researchers should be able to enlarge each field using the familiar native resize handle when reviewing longer content.

Validation

• python -m pytest tests -q -p no:cacheprovider — 52 passed
• GitHub CI passed on Python 3.11 and 3.12
• git diff --check passed