Links can be bookmarked for a later look via a toggle button on the
card (🏷️/🔖), shown with a yellow border while flagged. A new
sidebar section "Merkliste" links to /?review=1, filtering to just
the flagged links; the count updates live via the existing facets
query.
Since the project has no migration framework, add a minimal
startup check that ALTER TABLEs in the needs_review column for
existing SQLite databases (create_all only creates missing tables).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
b6a236527e