#3088 feat: redesign pane layout system (@superset/panes)

Summary

• Redesigned the pane layout data model from a 3-tier hierarchy (Root → Group → Pane) to a simpler Tab → Split → Pane model
• Renamed package from @superset/pane-layout to @superset/panes
• New store with all actions (tab CRUD, pane CRUD, split/resize/equalize, openPane, replacePane)
• N-ary weighted splits (FlexLayout-inspired) with react-resizable-panels for resize UI
• React component tree: Workspace → TabBar → Tab → Pane with PaneHeader
• Configurable pane header actions via PaneActionConfig (split + close with hotkey tooltips)
• Slots API: renderTitle, renderHeaderExtras, renderToolbar (full eject) on PaneDefinition
• PaneContext and TabContext types with enriched layout info (parentDirection, position)
• 57 store tests passing
• Wired up in desktop app's v2 workspace with proper pane registry, empty state, and command palette

Test plan

• Open v2 workspace → empty state with action buttons renders
• Click + → dropdown shows Terminal/Chat/Browser options
• Add terminal tab → tab appears with pane header (icon + title + split/close)
• Click split → new terminal pane appears (direction auto-picks based on layout)
• Click close → pane closes, last pane closes tab
• Resize split handles → weights update
• Tab rename (double-click) → inline input works
• Tab context menu → Rename/Close/Close Others/Close All
• Hover pane header actions → tooltips with hotkey labels
• bun test in packages/panes → 57 tests pass
• bun run typecheck in packages/panes → clean

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Summary by cubic

Redesigned the pane layout to a simpler Tab → Split → Pane model using the new @superset/panes package. Integrated into the desktop v2 workspace with weighted splits, resize, a streamlined Add Tab menu (with Show Preset Bar toggle), and a cleaner empty state.

• New Features

  • N‑ary weighted splits via react-resizable-panels with resize/equalize.
  • Store with actions for tab/pane CRUD and split/resize/equalize; open/replace supported.
  • Slots on PaneDefinition and configurable headers via PaneActionConfig with hotkey tooltips.
  • Add Tab dropdown (Terminal, Chat, Browser) wired to the command palette; includes “Show Preset Bar”.
  • 57 store tests added.

• Refactors

  • Removed legacy PaneViewer; empty state renamed to WorkspaceEmptyState.
  • Chat components moved under the pane registry and renamed to ChatPane.
  • Renamed @superset/pane-layout to @superset/panes; host-service CORS now respects DESKTOP_VITE_PORT for localhost/127.0.0.1; downgraded @mastra/core (1.17.0 → 1.16.0) and @pierre/diffs (1.1.7 → 1.1.3) to satisfy CI policy.