perf(ui): RepaintBoundary + TickerMode for workspace morph layers (Fluid F2)

[ZhuchkaTriplesix]

Parent

Part of #356 · Fluid perf audit F2 (P0)

Problem

QueryaSwitchingBody / QueryaCrossFadeStack apply AnimatedOpacity (and slide) over full workspace trees (empty hero ↔ connected SQL/editor) without RepaintBoundary per layer. Inactive keep-alive children stay mounted under opacity 0 and may keep tickers/work running.

Where:

• lib/core/motion/querya_switching_body.dart
• lib/core/motion/querya_cross_fade_stack.dart
• callers: workspace_panel.dart, engine workspace homes

Expected

• Each morph layer wrapped in RepaintBoundary
• Inactive layers use TickerMode(enabled: active) (keep IgnorePointer / ExcludeFocus)
• No new hard-cut regressions for empty ↔ connected

Acceptance

• Layers isolated for paint
• Inactive panes do not drive animation tickers
• Widget tests for SwitchingBody / CrossFadeStack still green
• Manual: empty ↔ connect morph stays smooth (profile preferred)

Related

• Epic Fluid: epic(ui): Fluid morphing — evolve QueryaMotion (post-0.4.11 shell) #342
• Checklist: docs/perf-baseline.md §9 Empty ↔ connected

[ZhuchkaTriplesix]

Fixed and merged via PRs #367/#368/#369 on dev.