fix(ui): keep a tool-call group collapsed until the reader opens it

[Astro-Han]

Summary

A turn with multiple tool calls rendered its group expanded, and it stayed expanded forever. ToolTrow seeded Astryx ChatToolCalls with defaultIsExpanded={items.some(isInFlightToolStatus)} so a live group would open, but that prop is uncontrolled: it sets the initial state only, and the timeline key is deliberately stable so a disclosure survives mid-turn inserts. A group opened while running therefore never re-collapsed, and every live turn left a trail of permanently open groups behind it.

This drops the custom seed and returns to Astryx's own default — collapsed. Opening a group is the reader's move, never the turn's.

The accepted trade-off, now recorded in the comment the workaround used to justify: a collapsed header projects the last call alone, so with parallel calls the last one can settle first and the header may briefly show a settled icon while a sibling still runs. It resolves as the group finishes, and expanding shows every row's real status.

Verification

• npm run test -w @maka/ui — 341/341 pass. Three suites asserted the expanded-by-default seed and now assert the collapsed default: tool-activity-presentation, tool-trow-stability, processing-block.
• node --test on the desktop renderer contracts that touch this surface (streaming-handoff, tool-error-collapse-contract) — 12/12 pass.
• npm run typecheck, npm run format, npm run lint — clean.
• apps/desktop/e2e/disclosure-output.spec.ts and the fixtures.ts readiness selector already gate on a collapsed row (single call), so they are unaffected. The Storybook stories in packages/ui/stories/tool-activity.stories.tsx render settled items and already rendered collapsed.
• Not run: full npm run test -w @maka/desktop is green except 14 pre-existing failures in project-root/workspace-picker suites, which resolve macOS temp paths and never import the UI package; Playwright E2E was not run locally.