Refactor workflows: extract shared cgroup script, add framework integ…

[JamesonRGrieve]

…rations

• Extract cgroup_workers.sh shared script for DRY CPU detection logic

  • Removes ~420 lines of duplicated code across 8 workflows
  • Single source of truth for cgroup-aware worker calculation

• Refactor test-py-unittest.yml to simple runner pattern

  • Reduces from 1471 lines to 535 lines
  • Now compatible with run-branch-test.yml framework
  • Comparison logic delegated to regression-test.yml

• Refactor test-storybook.yml to test-js-storybook.yml

  • Simple runner pattern matching other test workflows
  • Removes composite comparison logic (handled by run-branch-test.yml)

• Add NUnit, xUnit, unittest, and Storybook to run-branch-test.yml

  • Full source/target/compare job chains for each framework
  • Framework auto-detection for .NET and Storybook projects
  • Aggregated regression counts in notifications

• Fix missing xfailed_count output in .NET workflows

Note: test-py-bandit.yml intentionally kept as security scanner (different purpose than test runners)