fix(workflows): freeze settled launch cards

[tt-a1i]

Summary

• freeze settled Workflow tool-result cards to their launch details and render timestamp
• keep live status and spinner invalidation only while Pi still marks the tool result partial
• make elapsed-time rendering accept the caller timestamp so a frozen card has no hidden wall-clock dependency
• preserve the existing live strip, dashboard, completion delivery, and synchronous wait behavior

Root cause

Detached Workflow runs remained in activeRuns after their launch receipt settled. renderResult therefore kept a 120ms transcript timer and also reread live details plus Date.now() on unrelated redraws, mutating a historical regular-mode card above the viewport.

Validation

• deterministic execute-level regression: a real detached run remains active behind a settled launch result; over multiple spinner intervals it emits zero transcript invalidations and renders byte-stably
• partial Workflow card, strip, and dashboard spinner tests remain green
• bun run check
• bun run test (870 Node tests, 30 Vitest tests)

Manual TUI smoke

• attempted an isolated Ghostty + current-worktree launch without changing the installed OpenPI source
• automated scroll interaction could not proceed because the local Computer Use safety policy disallows Ghostty access
• Ghostty regular/fullscreen scroll-anchor smoke from Workflow 后台运行时历史工具卡持续动画可触发 Pi regular 全量重绘，用户上滚位置丢失 #96 remains a manual merge gate

Addresses #96