feat(pipeline): optimize build performance with incremental builds, caching, and metrics dashboard

[PAMulligan]

Summary

• Add incremental build system with content-hash based caching to skip unchanged phases
• Add stage profiling for timing, memory tracking, and slow stage detection
• Add performance metrics dashboard with HTML/Markdown visualization
• Add parallel execution mode for independent pipeline phases

New Scripts

Script	Purpose
scripts/pipeline-cache.js	SHA-256 content-addressable caching with phase-level invalidation
scripts/stage-profiler.js	Timing, memory metrics, historical trends, slow stage analysis
scripts/metrics-dashboard.js	HTML/Markdown dashboard with cache efficiency and trends
scripts/incremental-build.sh	Orchestrates cached builds with optional parallel execution

Key Features

• Hash-based caching: Skips phases when input files haven't changed
• Stage profiling: Tracks duration and memory for each pipeline stage
• Trend analysis: Detects performance degradation over time
• Slow stage alerts: Configurable thresholds for warning on slow stages
• Metrics dashboard: Visual summary of build performance and cache efficiency

Usage

# Run incremental build (uses cache)
./scripts/incremental-build.sh

# Force rebuild ignoring cache
./scripts/incremental-build.sh --force

# Run with parallel phases
./scripts/incremental-build.sh --parallel

# View cache status
node scripts/pipeline-cache.js status

# Generate dashboard
node scripts/metrics-dashboard.js generate

Test plan

• Run ./scripts/incremental-build.sh to verify full quality gate
• Run twice to verify cache hits on second run
• Run with --force to verify cache bypass
• Run node scripts/pipeline-cache.js status to verify cache tracking
• Run node scripts/metrics-dashboard.js generate to verify dashboard generation

🤖 Generated with Claude Code