refactor(client): shared row-docs badges across sections

Extract MissingDocsBadge and RowDocsPanel so every per-row document
placement renders the same incomplete-pages feedback, replacing the
copy-pasted docs boxes in the dependents and education form sections.
Surface the badge on collapsed repeater headers and education table
rows, let read-only views opt in via an optional missingFor prop
(SectionRepeaterTable cells now accept nodes), and drop
DependentsView's hand-rolled duplicate.