feat: add in-progress PR validation comment

[vreshch]

Summary

• Adds an in-progress comment at the start of PR validation so reviewers see current status instead of stale results while CI runs.

Test plan

• Open a PR and verify the in-progress comment appears immediately
• Verify the final comment replaces the in-progress one

[github-actions]

🎉 PR Validation ✅ PASSED

Commit: 297a8e4741ab0fd901cdef1b64549bef4f266e78
Branch: feat/pr-in-progress-comment

Checks:

• ✅ Dependencies installed
• ✅ Linting passed
• ✅ Format check passed
• ✅ Build successful
• ✅ Docker build
• ✅ E2E tests

Visual Changes: 5 of 20 screenshots changed

📸 downloads dark desktop — 100% changed

📸 downloads dark mobile — 100% changed

📸 downloads light desktop — 100% changed

📸 downloads light mobile — 100% changed

📸 home dark mobile — 1.222% changed

Before	After	Diff

Ready to merge! ✨

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🔗 View workflow run
⏰ Generated at: 2026-04-01T21:38:09.093Z