Add CI matrix + RC-tag integration gate

[ewega]

Summary

• add .github/workflows/ci.yml for unit validation on PRs/pushes (Linux, Windows, macOS)
• add .github/workflows/integration.yml for integration validation on workflow_dispatch and �*-rc* tags
• keep full connection/scope/project E2E on GitHub runners; use local �ct smoke path for deploy/health/migration
• update .github/workflows/release.yml to skip RC tags (if: !contains(github.ref_name, '-rc'))
• fix cross-platform compose path fallback in cmd/deploy_local.go using ilepath.Join

Validation

• go test ./... (pass)
• local �ct integration run passed in smoke mode:
  • �ct --pull=false -W .github/workflows/integration.yml -j integration -s DEVLAKE_TEST_PAT=...

Notes

• DEVLAKE_TEST_PAT is required for full GitHub-runner E2E connection setup.
• optional overrides for full E2E: DEVLAKE_TEST_ORG, DEVLAKE_TEST_REPO.

[Copilot]

Pull request overview

This PR enhances the CI/CD infrastructure by adding comprehensive testing workflows and fixing a cross-platform path handling issue. The changes introduce a multi-OS CI matrix for unit tests and a dedicated integration testing workflow that supports both local (act) and GitHub runner execution, while ensuring RC tags trigger integration validation but skip releases.

Changes:

• Add .github/workflows/ci.yml for cross-platform unit testing (Linux, Windows, macOS) on PRs and pushes to main
• Add .github/workflows/integration.yml for E2E integration tests triggered by workflow_dispatch or RC tags, with smart act/GitHub runner differentiation
• Update .github/workflows/release.yml to skip RC tags using !contains(github.ref_name, '-rc')
• Fix cross-platform path construction in cmd/deploy_local.go by replacing hardcoded Windows path separator with filepath.Join

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
.github/workflows/ci.yml	New cross-platform unit test workflow running build/vet/test on Linux, Windows, and macOS for PRs and main branch pushes
.github/workflows/integration.yml	New integration test workflow with deploy/health/migration smoke tests (act) and full connection/scope/project E2E (GitHub runners)
.github/workflows/release.yml	Add RC tag filter to prevent release workflow from running on pre-release tags
cmd/deploy_local.go	Replace hardcoded Windows path separator with filepath.Join for cross-platform compatibility