CI Performance Optimization: Reduce workflow time from 40+ min to <15 min

[jongio]

Problem

CI workflow currently takes 40+ minutes to complete, creating slow feedback loops for PRs and blocking development velocity.

Current Bottlenecks

• Preflight Checks: 9.0 min (blocks everything)
• Test (Windows): 6.2 min
• Integration Tests (Windows): 4.6 min
• Repeated setup overhead: Go/Node/pnpm/dashboard build duplicated 8+ times
• Inefficient dependencies: Build blocked by unnecessary preflight wait

Solution

Three-phase optimization strategy targeting 60%+ runtime reduction:

Phase 1: Caching & Setup (-10 min expected)

• Create composite setup action (eliminate 8x duplication)
• Implement aggressive caching (Go modules, pnpm, dashboard builds)
• Build dashboard once, reuse across jobs

Phase 2: Parallelization (-12 min expected)

• Remove blocking dependencies (build doesn't need preflight)
• Split preflight into quick-checks + parallel security-scan
• Optimize test matrix (Ubuntu full, Windows smoke, remove macOS integration)
• Parallelize platform builds

Phase 3: Advanced (-5 min expected)

• Conditional execution for doc-only changes
• Test suite optimization
• Final tuning

Goals

Primary:

• Total CI time <15 minutes (60%+ reduction)
• Critical path <10 minutes

Secondary:

• Maintain all security scans (gosec, govulncheck)
• Keep platform validation (all 3 OSes for unit tests)
• Zero increase in test flakes

Specification

Full details in: docs/specs/ci-perf/spec.md

Tasks: docs/specs/ci-perf/tasks.md

Success Criteria

• ✅ Total CI time <15 minutes
• ✅ Cache hit rate >75%
• ✅ All tests passing
• ✅ All security scans maintained
• ✅ Documentation updated