Rebuild /display left rail for editor-completion Phase 1 fidelity

[WilfordGrimley]

Summary

Phase 1 of the owner-approved editor-completion package (authority: the editor-completion spec + mockup scoped in #244) — the left-panel fidelity rebuild on /display. Visual foundation only; no interactions.

• E1–E6: filters collapsed by default (additive initialSettingsVisible on useGridSelectorSearch), full-width stacked disclosure (additive layout="stacked" on SelectVersionResults, additive hiddenSections on GridSelectorFilters), Group-by/Facet removed from the rail, card-display-style toggle removed (compressed hard-pinned true), artist line + a confidence-element placeholder promoted always-visible above the fold.
• §7.5: CardDetailedViewModal's body extracted into CardDetailedViewBody.tsx (behavior-preserving, region-level sub-blocks: identifier copy, meta table, download/favorite, printing tags, report). The rail's demoted Card Details/Printing Tags/Report sections reuse the same sub-blocks, lazy-mounted so opening a slot doesn't fire their backend fetches until the section is actually expanded.
• E18/E20: dark (never-white) empty/loading/failed sheet slot states — grey-pinline background on both the slot div and its <img> (kills the white pre-paint flash), an animated loading bar, and a failed state with a muted ✗ plus a deterministic Scryfall "Find this card ↗" link (zero-crawl: URL constructed from the query, never fetched).
• E19: lime rounded corner-only cut guides on screen. Confirmed upstream (upstream/master's PDF.tsx) already has the corner-only geometry (CutLineCorner, cutLineShape: "InsideOnly") — built the screen-side guide on that existing shape rather than reinventing it. True PDF-side color/preset parity is not shipped in this PR (see Deviations).

All shared-component changes are additive-optional props; existing callers (GridSelectorModal) are unaffected.

Deviations from spec

1. Confidence element (ConfidenceElement.tsx) is the narrower placeholder the task explicitly scoped: no live vote dispatch, no Scryfall hover popover, and the "not this printing" button only renders for a suggested printing — the mockup also shows it for the confirmed state, which this PR does not replicate. D14 is flagged in the spec as needing further definition; this is a deliberate stopping point, not an oversight.
2. E19 PDF-side parity deferred: the screen preview's lime corner guides ship; the actual exported PDF's cut-line color/preset is not changed in this PR (out of this task's screen-only cut; upstream's shape machinery is confirmed reusable when that's picked up).
3. FilterChipBar relocated, not deleted: the spec's literal wording ("chip wall folded away... removed from this surface") was read as "folded into the Filters disclosure" rather than deleted outright, since it's real, tested functionality (art-as-filter, "More like this"). It now lives inside the (collapsed-by-default) Filters section instead of always-visible.
4. Lazy-mounted demoted sections: Card Details/Printing Tags/Report only fetch their backend data once their accordion section is actually expanded, rather than on every slot selection — an addition beyond the literal spec, to avoid new unconditional backend traffic per click.
5. Two pre-existing Playwright flakes (unrelated to this change, confirmed via A/B testing against unmodified origin/master) remain: a phone-viewport dialog-count race and the D17 sheet-position-pill race under scroll timing. The latter is documented in docs/troubleshooting.md.

Test plan

• npx tsc --noEmit clean
• npx prettier@2.7.1 --check clean on all changed files
• npx eslint --fix applied, next lint clean
• CardDetailedViewModal.visual.spec.ts passes unmodified — the extraction's acceptance proof
• DisplayPage.spec.ts updated for the new rail structure (selectors moved, none loosened), passes except the pre-existing D17 flake noted above
• SelectVersionSection.spec.ts updated (Filters now needs opening for the two filter-chip tests), passes
• New DisplaySlotStates.spec.ts (4 tests) — asserts computed background-color is never white across filled/loading/failed/empty-select-version states, plus the Scryfall link's presence; passes
• Live-browser screenshot comparison against the mockup at 1400px (dark rail theme, promoted header/artist/confidence zone, always-open Select Version, demoted accordion order) — visual match confirmed, temp comparison specs not committed
• docs/features/grid-selector.md updated in place for the rename/promotion; docs/troubleshooting.md gained the D17 flake entry

Extractable-primitives ledger: checked — CardDetailedViewBody's sub-blocks (PrintingTagsBlock, ReportBlock) remain entangled with the tag-vote/consensus system, so this extraction does not produce a clean new ledger row. No ledger change made.

Wiki checklist (merge-time)

• wiki: /display (Editor) page needs a note that the left rail now opens with Select Version expanded and Filters collapsed, with Card Details/Printing Tags/Report moved into a demoted, lazy-loading accordion below it.

Do not merge — awaiting owner review, per this task's explicit instruction (Phase 1 of a multi-phase package; interactions/context-menu/drag/multi-select/undo are Phase 2 and intentionally not built here).

Closes nothing (umbrella tracking against the editor-completion spec, not a single issue).

[WilfordGrimley]

Superseded by #319 (merged): identical content recut onto post-#317 master after this branch's merge state became unresolvable. Branch left in place per the no-delete-on-close convention; cleanup pass later.