feat(CI): add upgrade test

[kamuikatsurgi]

Description

Adds a workflow that tests rolling upgrades of bor on a PoS devnet. Deploys a devnet with :latest images, builds bor:local from the PR code, runs the upgrade script to roll all nodes from :latest to bor:local, then runs a post-upgrade health check (block production, node sync, milestones, checkpoints, L1→L2 bridge state syncs).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 49.62%. Comparing base (6b0405c) to head (697afb1).
⚠️ Report is 94 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2070      +/-   ##
==========================================
- Coverage   51.63%   49.62%   -2.01%     
==========================================
  Files         877      873       -4     
  Lines      155302   150641    -4661     
==========================================
- Hits        80190    74761    -5429     
- Misses      70012    70822     +810     
+ Partials     5100     5058      -42     

see 49 files with indirect coverage changes
see 49 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

This PR is stale because it has been open 21 days with no activity. Remove stale label or comment or this will be closed in 14 days.

[github-actions]

This PR is stale because it has been open 21 days with no activity. Remove stale label or comment or this will be closed in 14 days.