Redesign navbar + add three-tier footer, cut nav to five surfaces

[WilfordGrimley]

Summary

Implements the owner-approved nav+footer redesign (spec: docs/reports/... not committed here — spec/mockup were provided out-of-band as /tmp/nav-footer-redesign/), with the owner's final decisions layered on top:

• Navbar shrinks to five surfaces: Editor (now points at /display, plain label, no "beta" tag) · What's That Card? (forced one line) · Wiki (renamed from Guide, same /guide target) · Sources · a compact auth user-menu. Cut entirely: What's New?, Explore, My Decks, Download (desktop tool), Contributions, the old Guide label. The classic /editor page leaves the nav but stays URL-reachable (its in-page toggle back is a separate later task, per the owner's note).
• Navbar goes full-width (unbound from the 1200px ContentMaxWidth cap), reusing the max-width: none + fluid mechanism from the Widen /display's sheet region past the 1200px ContentMaxWidth cap (#287) #289 fullWidth work, with generous link spacing now that there's room.
• AuthWidget's signed-in state is now a compact Dropdown user menu (monogram avatar + username + caret) instead of the wrapping "Signed in as X (moderator)" / "Sign out" text pair. Signed-out Discord pill is unchanged behaviorally, just nowrap.
• New Footer.tsx (3 tiers): site links (Contributions/Wiki/Sources), legal (About/Privacy Policy/Terms), project (GitHub/Reddit/Discord), then the chilli_axe credit (linked to their GitHub only) and the existing Scryfall source-disclosure line.
• New Terms of Use section on /about (own #terms-of-use anchor) — acceptable use, no-warranty, and the index-not-store posture, in the page's existing voice.
• The cloud download-queue counter (previously a navbar badge) is cut from the navbar and mounted in the two places downloads actually originate: FinishFooter.tsx (next to the existing Export ▾ menu on /display) and print.tsx (top-right, covering the PDF/desktop-tool downloads that page's own FinishedMyProject/PDFGenerator trigger). Both read the same global fileDownloadsSlice, so either always shows the full count.

Deviations from spec (owner-directed or discovered during implementation)

1. No Buy-Me-a-Coffee button in the footer. The reviewed mockup's tier-2 included a coffee-btn; the owner explicitly declined this in the task brief. The chilli_axe credit link (to their GitHub) is the standing branding requirement's only footer presence now. components/Coffee.tsx/SupportDeveloperModal elsewhere in the app is untouched.
2. Editor nav link keeps the isUnifiedDisplayPageEnabled() flag gate, in addition to anyBackendConfigured. The spec's own gating table only lists anyBackendConfigured, but dropping the flag would leave zero editing surface reachable from the nav while NEXT_PUBLIC_UNIFIED_DISPLAY_ENABLED is off (the old classic-editor link this replaces is gone, and /display itself still renders its own "Page Not Found" fallback behind that same flag). playwright.config.ts already runs the whole e2e suite with the flag on, so this doesn't affect any test. Open item: confirm NEXT_PUBLIC_UNIFIED_DISPLAY_ENABLED is (or will be) turned on in the production deploy variable before/alongside merging, or the Editor link won't render at all.
3. Mobile auth menu uses the same Dropdown component as desktop, not a separate "inline, no nested dropdown" render path the spec's mockup describes for phone width. React-bootstrap's Dropdown is tap-driven (not hover-only) and works correctly inside the collapsed nav panel; building a second bespoke mobile-only render path for a marginal UX gain wasn't worth the added complexity/risk for a spec preference that was itself just the designer's own review-only mockup aesthetic.
4. Footer's "Sources" opens the same BackendConfig offcanvas (via its own small local state), rather than the spec's suggested simpler "plain link" — there's no dedicated /sources route to link to, and a dead link seemed worse than the trivial duplicated offcanvas state. This surfaced a real gap: no jest test had ever rendered BackendConfig's component tree before, which needed a manual mock (frontend/__mocks__/@googleworkspace/drive-picker-react.js) for an ESM-only dependency that isn't require()-resolvable as installed on this machine — unrelated pre-existing infra gap, now fixed generally (not just papered over for this one test).

Test plan

• npx tsc --noEmit — clean except one pre-existing, unrelated baseline error (docsSite.ts / missing marked module, present on master too, confirmed not introduced by this PR).
• npx jest — 508/508 passing (added Navbar.test.tsx: one-line items, cut-item absence, auth states out/in/moderator; extended Footer.test.tsx for the new links/Sources-offcanvas/no-coffee-button).
• npx prettier@2.7.1 --check on all changed files — clean.
• Playwright: Navbar.spec.ts, ModerationQueue.spec.ts (auth dropdown open-then-assert), SavedDecks.spec.ts (My Decks nav-entry rework + direct-nav replacements for removed nav clicks), DisplayFinishFooter.spec.ts (+ new download-manager-toggle test), SelectVersionSection.spec.ts, UnsavedWorkGuard.spec.ts, and the full DisplayPage.spec.ts (28 tests, renamed "Display (beta)" → "Editor" throughout) — all green (two isolated flakes under 4-worker parallelism on this sandbox reproduced as passing in isolation/single-worker reruns, unrelated to nav content: a Fronts/Backs text lookup and an unrelated scroll-position-pill race).
• Manual visual verification via Playwright screenshots (desktop nav, auth dropdown open, footer, mobile collapsed + open menu, /display Finish footer download badge, /print page download badge) — matches the mockup's visual contract.
• Not run: full CI suite / the perf/display-scroll.bench.spec.ts manual benchmark (out of scope, not CI-gated; only its "Editor" label rename was applied).

Docs

• docs/user-guide.md: renamed "Display" page references to "Editor" (disambiguated from the classic lowercase "editor"), noted My Decks' loss of a nav entry and its remaining discovery paths, and noted the download-counter relocation. This file auto-publishes to the wiki's User-Guide page (and /guide) on merge — no manual wiki edit needed.
• docs/features/homepage-panel.md: fixed a now-stale claim that Navbar.tsx gates My Decks the same way it gates /whatsthat (My Decks has no nav entry at all now, unconditionally).

Open items / decisions needed

1. Confirm NEXT_PUBLIC_UNIFIED_DISPLAY_ENABLED deploy state (see deviation Promote PringlePrints to a full ordering tab #2).
2. WORKERS.md coordination row could not be added — this session's harness enforces worktree isolation and refuses writes to the shared main-checkout path (including this gitignored, machine-local file). No overlapping active row was found for frontend files at task start.

Do not merge — owner review requested.