Clarify import review counts and untouched field validation

[beanbean9339]

Closes #55

Changes

• Label review findings, import warnings/errors, field-review counts, and health-scan check counts by what they actually measure.
• Keep required-field markers visible while deferring error styling/messages on untouched fields, including after import. Reset touched state when a new import succeeds; show all field errors when the user attempts an invalid export.
• Preserve the existing metadata validation and export blocking logic.
• Add SSR rendering tests for required, touched, and export-attempt states and tests for review headline categories.

Validation

• npm run test (106 passed)
• npm run build (passed)

Independent branch based on main; does not change PR #64.