fix(tasks): download artifacts without pop-ups

[tatoalo]

Problem

Artifact downloads were blocked in the desktop and web hosts because opening a new tab requires pop-up permission. Follow-up to #3788.

Changes

Fetch the presigned artifact directly and trigger a local blob download with the original filename. This avoids pop-ups and keeps image artifacts from replacing the app.

How did you test this?

• pnpm --filter @posthog/ui exec vitest run src/features/sessions/components/CloudArtifactDownloads.test.tsx
• pnpm --filter @posthog/ui typecheck
• pnpm biome check packages/ui/src/features/sessions/components/CloudArtifactDownloads.tsx packages/ui/src/features/sessions/components/CloudArtifactDownloads.test.tsx

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

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Created with PostHog Code

[trunk-io]

😎 Merged directly without going through the merge queue, as the queue was empty and the PR was up to date with the target branch - details.

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 5080706.}

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

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### Issue 1 of 1
packages/ui/src/features/sessions/components/CloudArtifactDownloads.tsx:73
**Desktop blocks the blank popup**

When a user downloads an artifact in the Electron app, the desktop window handler unconditionally denies this `window.open` call, causing the function to return with an “Allow pop-ups” toast instead of opening the file.

_{Reviews (1): Last reviewed commit: "fix(tasks): preserve user activation for..." | Re-trigger Greptile}