[v0.7] User-initiated publication check and metadata completion

[JUhalt]

Goal

Help researchers notice when a tracked manuscript may have been published, and fill missing metadata — only when they ask, and never by changing status on their behalf.

Scope

• Check for publications: for selected manuscripts that are not yet Published, look up possible matches by DOI and normalized title through Crossref and, optionally, a user-entered ORCID iD's public works.
  • Results read "A publication matching this manuscript may have appeared" with Review match, Mark Published, and Ignore.
• Fill blanks from Crossref: batch completion for selected records that fills only empty fields, with a preview of every change.
• Both are user-initiated from the Import & Export page ([v0.6] Import & Export page #58) or a manuscript page. There are no background network checks.
• Unreviewed possible matches can appear in the Deadline Center / Needs Attention ([v0.7] Deadline Center #28) as review items.

Acceptance

• Stage, shelf, target journal, and history change only through an explicit Mark Published choice, which records a normal lifecycle event.
• Fill blanks never overwrites a non-empty field.
• Network failure or rate limiting leaves records unchanged and is reported clearly.
• If ignored matches are remembered, storage uses a conservative migration with backup/restore coverage.
• Matching and field-merge logic are unit-tested with synthetic Crossref/ORCID responses.

[JUhalt]

Planned as slice C of v0.7 (draft PR #78; the design mockup is linked there). Settled: possible and ignored matches are remembered, so this is v0.7's one storage change (Schema 7, with a conservative migration and backup/restore coverage). Checks run only when you ask, from Import & Export or a manuscript's ⋯ menu. A match is reviewed side by side, and Mark Published is the only way status changes. Fill blanks previews every field and never overwrites a non-empty one. Unreviewed matches wait in the Deadlines page's No date group.

[JUhalt]

Released in v0.7.0 (PR #78, PR #81). Certification: #79.