fix(components): align live activity status spacing

[wibus-wee]

The live Thinking/Working status sat flush against the preceding assistant content because it renders inside a footer row that suppresses top padding. Restore the 4px prose/activity-summary gap, and use the existing 12px object gap when the preceding row is a bordered task, plan, or tool surface.

Validation:

• pnpm install --frozen-lockfile
• pnpm --filter @lody/e2e check
• pnpm --filter @lody/components exec vitest run tests/agent-activity-row.test.tsx tests/assistant-turn-action-inset.test.ts (15 tests passed)
• pnpm --filter @lody/components typecheck
• pnpm exec oxfmt --check packages/components/src/components/ai-gui/view.tsx
• pnpm run docs check
• pnpm format
• Storybook browser measurement confirmed a 12px gap below a live subagent task card while prose keeps 4px
• Desktop E2E smoke passed after rebasing onto the synchronized lockfile

Root pnpm check passed typecheck and lint, then reached test:ci; the components suite failed in 22 files because Node 26 exposes no usable global localStorage without --localstorage-file (124 failures, all from that environment issue).

[github-actions]

Desktop PR regression failed on commit 9a6452db7b4c9b2e191ce9f9ab51a20930e037ea.

• Workflow run: https://github.com/LodyAI/Lody/actions/runs/35506104095
• Failed scenarios indexed: 0
• Recording: 1/1

Recordings not attached

• Run evidence: failure-index.json is missing

The Actions artifact retains the complete trace, screenshots, logs, and runtime evidence.