[task] Standardize engine installation steps using template method pattern

[github-actions]

Objective

Eliminate 80% code duplication in engine installation steps by extracting common patterns to a base implementation using the template method pattern.

Context

Part of issue #4640 - Priority 3 (Quick Win)

All engine files (claude_engine.go, codex_engine.go, copilot_engine.go) implement GetInstallationSteps() with 80% identical code. The only differences are configuration parameters (secrets, package names, versions).

Approach

1. Create a base installation helper in pkg/workflow/engine.go:

   • Define EngineInstallConfig struct with fields: Secrets, DocsURL, NpmPackage, Version, Name, CliName
   • Implement GetInstallationSteps(config EngineInstallConfig, workflowData *WorkflowData) []GitHubActionStep
   • Include common steps: secret validation and NPM installation

2. Simplify each engine's GetInstallationSteps() implementation:

   • Create config with engine-specific values
   • Call base GetInstallationSteps()
   • Add engine-specific steps (network permissions, settings, hooks) after base steps

3. Maintain engine-specific customization while eliminating boilerplate

Files to Modify

• Update: pkg/workflow/engine.go (add base installation method)
• Update: pkg/workflow/claude_engine.go (use base method + Claude-specific steps)
• Update: pkg/workflow/codex_engine.go (use base method + Codex-specific steps)
• Update: pkg/workflow/copilot_engine.go (use base method + Copilot-specific steps)

Acceptance Criteria

• EngineInstallConfig struct created with all required fields
• Base GetInstallationSteps() method implemented
• All three engines refactored to use base method
• ~200 lines of duplicate code eliminated
• Engine-specific customization preserved
• All existing tests pass (make test)
• Successful compilation (make build)
  Related to [refactor] 🔧 Semantic Function Clustering Analysis - November 2025 #4640

AI generated by Plan Command for #4640