perf(ui): pause work in inactive keep-alive workspace panes (Fluid F6)

[ZhuchkaTriplesix]

Parent

Part of #356 · Fluid perf audit F6 (P1)

Problem

Keep-alive morph stacks leave inactive Server/SQL/stats bodies mounted at opacity 0. Pollers, timers, or editor work can continue offscreen (overlaps with F2 TickerMode, but covers application work too).

Where: workspace homes using QueryaSwitchingBody / QueryaCrossFadeStack (e.g. postgres workspace home, workspace_panel.dart)

Expected

• When a pane is inactive: pause stats polling / non-essential timers
• Coordinate with F2 TickerMode (animations off when inactive)
• No data loss when switching back

Acceptance

• Inactive pane does not schedule periodic network/stats work
• Switching back resumes cleanly
• Tests or clear manual steps in PR

Related

• Pairs with F2

[ZhuchkaTriplesix]

Fixed and merged on dev via Fluid perf PRs.