feat: minimal workbench shell redesign (0166)

[crs48]

Implements docs/explorations/0166 — the xNet Workbench: a fixed-region, monochrome, keyboard-first shell that replaces the header + sidebar layout.

What changed

Phase 0 — Foundations (packages/ui)

• tokens.css rebuilt around a role-named, APCA-checked monochrome ramp (surface-0/1/2, ink-1/2/3, hairline, accent-ink) with all legacy semantic variables aliased onto it. Primary/ring are now monochrome ink; hue survives only for user data (status dots, charts). Includes a true-black OLED variant (ThemeProvider setVariant).
• 3-role type scale: Inter Variable (UI 13px / prose 16px) + Geist Mono, via fontsource.
• Shadows removed from primitives and composed components — hairline borders and dimming carry elevation; the modal scrim stays.

Phases 1–2 — Shell + tabs (apps/web/src/workbench/)

• Fixed regions: Rail (44px) · Left Panel · tabbed Editor Area · contextual Right Panel · Bottom Panel · Status Bar (24px, mono). Persisted zustand store (xnet:workbench:v1) + react-resizable-panels layout persistence.
• Everything opens as a tab; the router stays authoritative (deep links, back/forward, bookmarks unchanged). Preview-tab semantics (single click previews, editing/double-click promotes), pin, drag-reorder, middle-click close, Ctrl+Tab cycling, one optional split (drag-to-edge or ⌘⇧\). Background tabs are unmounted entirely — zero live Y.Doc subscriptions.
• Zen mode (⌘., Esc Esc exits) restores the prior layout bit-for-bit.

Phase 3 — Panels

• Explorer (pinned / recent / virtualized all-items with type filters) replaces the type-siloed sidebar; Tasks and Data left-panel views.
• Right Panel useContextPanel API: PageView publishes Properties/Comments/Backlinks (comments moved out of the page layout); DatabaseView row detail; CanvasView selection inspector; TasksView task detail.
• Bottom tray: Shelf, quick capture, notifications, sync activity, and a query console (paste a SavedViewDescriptor/QueryAST → table via SavedViewRunner). Saved views are first-class tabs (/view/$viewId).

Phase 4 — Keyboard & palette

• GlobalSearch rebuilt on cmdk: quick-open (recents first, full-text pages, all node types), > command mode, chords on every row, ⌘K/⌘P, Escape restores focus. Measured open→focused ~1ms (50ms budget).
• Shell focus ring: F6/⇧F6 cycle regions; Escape in a panel returns to the editor.

Phase 5 — Unified drag

• application/x-xnet-node payload (packages/ui/src/dnd/node-transfer.ts) on explorer rows, tabs, My Tasks rows, the database row-detail chip, and the canvas selection pill (drag a card out and you carry its source node — excerpting, not copying).
• Reference-creating drops: editor → wikilink chip at the drop point, relation cells → link, canvas → source-backed card, tab bar → tab, editor edge → split, Shelf → held reference.

Phase 6 — Extensibility & flip

• StatusBarContribution added to @xnetjs/plugins; SidebarContributions become rail items/panel views; CommandContributions mirror into the CommandRegistry; configurable startup tab.
• Flag removed; legacy shell deleted; docs/reference/WORKBENCH.md added.

Validation

• Full vitest suite: 476 files / 6,465 tests pass; CI editor-ux Playwright specs (desktop + mobile) pass unmodified.
• Production cold start (reload → interactive editor): 308ms (budget 1.5s); palette ~1ms (budget 50ms).
• Layout/tabs/zen survive reload bit-for-bit (state-diff verified); back/forward move between tabs.
• APCA: light ink Lc 105/86/60, dark ink Lc 96/62/32 (dark ink-2/3 brightened vs the exploration table to actually meet the ≥60/≥30 targets); WCAG AA passes for body/secondary.

Deviations from the exploration doc

• Dark ink-2/ink-3 are #B4B4B4/#7A7A7A (doc's #9A9A9A/#5C5C5C measured Lc 48/19, below its own validation targets).
• Split is ⌘⇧\ (Mod-|); ⌘\ stays on the right panel per the doc's keyboard map.
• In-grid row drag stays on dnd-kit (reorder) — rows drag out via the row-detail chip; ProseMirror block drag untouched.
• Two validation items remain open by nature: a fully mouse-free comment flow (editor selection toolbar is pointer-bound) and the first-run hallway test (needs humans).

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Redesigned workbench with tabbed editor, resizable panels, and split-view support
  • Page editor with integrated comment threads, replies, and orphaned comment handling
  • Saved views system for querying and displaying data
  • Improved global search and command palette with keyboard shortcuts
  • Context panels showing selection details, task info, and database rows
  • Zen mode for distraction-free editing
  • Drag-and-drop support across pages, databases, canvases, and shelves
  • Theme variant support including true-black for OLED displays
  • Quick capture tray for fast task creation
  • Explorer panel with pinning and recent items

• UI Improvements

  • Refined styling with updated monochrome token system
  • Removed drop shadows for cleaner design
  • Enhanced error fallback component

• Bug Fixes

  • Storage warning banner height tracking
  • Improved node transfer and drag-drop handling