feat: PDF export, evidence report, date filtering, S3 SSL toggle

[khanzzirfan]

Summary

This PR delivers several independent improvements across the server:

• S3 SSL toggle — adds S3_USE_SSL env var so users can disable TLS for non-SSL MinIO setups (was hardcoded true)
• PDF and evidence export — new download endpoints that generate PDFs via headless Chromium; evidence PDF embeds per-test screenshots with pass/fail badges

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Changes

Bug fix

• app/lib/storage/s3.ts — useSSL now reads from S3_USE_SSL env var (defaults true); was unconditionally true, breaking plain-HTTP MinIO deployments

New features

PDF / evidence export

• app/api/report/[id]/export/route.ts — ZIP and PDF export for a single report (renders the Playwright HTML report SPA via headless Chromium)
• app/api/download/[id]/route.ts — unified download handler supporting ?format=zip|pdf|evidence; the evidence format generates a standalone A4 PDF with summary stats, per-test outcome badges, file/line info, and embedded first screenshot per test
• Dockerfile — installs chromium via apk and sets PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH; copies all three Playwright packages (@playwright/test, playwright, playwright-core) into the standalone image and creates the npx playwright symlink

Docs

• .env.example — S3_USE_SSL documented
• readme.md — updated env var table and storage section

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Test plan

• S3/MinIO connection succeeds with S3_USE_SSL=false (plain HTTP endpoint)
• PDF download renders the Playwright HTML report correctly (auth-forwarding cookies tested)
• Evidence PDF contains per-test rows with embedded screenshots
• npx playwright test --project=api passes
• npx playwright test --project=ui passes
• Docker image builds cleanly (docker compose build --no-cache) and /api/ping returns 200