fix(init): compose templates with built-in skills

[codeaholicguy]

Summary:

• allow init template application and explicit built-in skill installation to run independently
• preserve template-only and non-template built-in behavior
• replace the prior silent-ignore assertions with regression coverage for templates with and without explicit skills

Validation:

• strict red/green TDD plus reverse-fix red/restored-green
• focused init tests: 23 passed
• CLI tests: 901 passed
• full workspace tests: all 6 projects passed
• CLI typecheck, workspace lint, and workspace build passed
• init E2E selection: 8 passed
• temporary-directory CLI composition and idempotency repro: 20 installed/configured unique built-ins across repeated runs

Caveats:

• the unfiltered E2E invocation was terminated by the execution harness before Vitest emitted its final summary; the complete init-command E2E subset passed
• lint retains six pre-existing unused-catch warnings and zero errors