docs: clear wiki-checklist debt for /display and What's That Card updates

[WilfordGrimley]

Summary

Clears the accumulated wiki-maintenance checklist items left by six recently-merged PRs, per CLAUDE.md's wiki-maintenance convention (docs/user-guide.md is the wiki+site-published guide; edits here regenerate the User-Guide wiki page and /guide/using-it, never hand-edited directly).

• PR Add /display dual-mode Add/Browse search bar + catalog browse (#267) #283 (dual-mode Add/Browse search bar + Import): added a paragraph to "Searching for cards" describing the Add/Browse toggle and the + Add Cards dropdown (verified the actual button label in Import.tsx — the PR's own body flags it as not literally "Import ▾" despite the mockup, so the guide describes what's actually on screen).
• PR Add /display sheet presentation + spacing defaults + Card Spacing control (#284) #296 / Add /display print defaults: Letter landscape, ET-8500 margin profiles, 3.175mm bleed (#286) #299 (Card Spacing + margin-profile Page Setup controls): Add /display print defaults: Letter landscape, ET-8500 margin profiles, 3.175mm bleed (#286) #299 had already added the Margin profile paragraph to "Exporting a print-ready PDF"; added the missing Card Spacing paragraph (0mm/14.5mm defaults, Link/Linked toggle) that PR Add /display sheet presentation + spacing defaults + Card Spacing control (#284) #296's own merge-time checklist flagged as not done.
• PR Add /display Finish footer with co-equal Save Deck/Print + save-before-PDF draft backup (#275) #306 (Finish footer): added a paragraph to "Exporting a print-ready PDF" covering the co-equal Save Deck / Print buttons, the Export dropdown, the local draft auto-backup note, and the save-before-print gate.
• PR Add /display landing cohesion with saved decks (#268) #293 (saved-decks landing panel): added a sentence to "Saving and re-using a project" noting the Display page's empty-project landing lists your saved decks directly.
• PR Quiz-reveal hero redesign for What's That Card? (#305) #308 (quiz-reveal hero redesign for What's That Card?): added a paragraph to the "What's That Card?" section describing the new layout (card + starburst left on a deep-blue field, word-by-word title animation, questions in a scrolling panel to the right, desktop-scrolls-questions vs. mobile-pins-card split) — verified docs/features/printing-tags.md's own Frontend section already reads correctly post-merge (PR Quiz-reveal hero redesign for What's That Card? (#305) #308 updated it directly), so only the user-guide needed this pass.

PR #303 (sitewide dark-chrome/orange retheme): no doc/wiki change needed — confirmed no docs/ file describes the old blue accent as current (PR #303's own body already checked this; independently re-confirmed via grep for the old hex values and "blue" theme language).

Verification

• python3 .github/scripts/docs_lint.py — clean.
• npx prettier@2.7.1 --check docs/user-guide.md — clean.
• Every added claim (button labels, control defaults, layout behavior) checked directly against the current frontend source (DisplayPage.tsx, FinishFooter.tsx, CardSpacingControl.tsx, SavedDecksLandingPanel.tsx, Import.tsx) and against each PR's own merged body, not just the task's framing — caught and fixed one drafting error this way (initially wrote "Import ▾" before confirming the rendered button actually reads "+ Add Cards").
• Not run: full Playwright/jest suite (no frontend code changed, docs-only PR).

Open items / decisions needed

None — all six PRs' merge-time wiki-checklist items are addressed by this change.

Not merging this myself — leaving for review per repo convention.