feat: add bootcamp metrics command for standalone codebase metrics

[Arthur742Ramos]

Summary

Adds a bootcamp metrics <repo-url> command — the codebase-metrics counterpart to bootcamp health.

The project already exposes the HEALTH.md engine as a standalone, LLM-free bootcamp health command. The parallel METRICS.md engine (computeCodebaseMetrics) had no standalone equivalent — you could only get those metrics by running a full generation. This closes that asymmetry.

What it reports

Scans any repo (local path or remote URL) and reports the deterministic metrics that power METRICS.md:

• Language breakdown with percentage bars
• Composition — source / test / doc / config / other file counts
• Sizing — total/average/median file size, size class, test-to-source ratio
• Top-level directory distribution
• Largest-file hotspots (review targets)
• Approachability score (0–100 + A–F grade) with human-readable drivers

$ bootcamp metrics ./my-repo
📊 Codebase Metrics
Repository: local/my-repo
196 files · 2.8 MB · size class: small

🟢 Approachability 82/100 (Grade: B)
  • Compact codebase (56 source files) is quick to navigate
  • Healthy test-to-source ratio (1.36)
  ...
Languages
  TypeScript     ████████████████████ 99.9% (130 files)
  ...

Flags

• --json — full CodebaseMetrics payload for scripting
• --check / --min-score — CI gate on the approachability score (exit non-zero when below)
• --branch, --max-files (routed past root-command flag collisions, same as health), --keep-temp, --verbose

Implementation

Mirrors health-command.ts in structure and reuses computeCodebaseMetrics verbatim, so the command output can never drift from METRICS.md. Repo resolution, scanning, cleanup, and the --check gate all follow the established pattern.

Testing

• 9 unit tests (DI-mocked resolve/scan/compute): report, --json, --check both directions, custom --max-files, local path, --keep-temp, scan-failure cleanup, resolve-failure.
• 4 E2E tests spawning the real CLI against a multi-language fixture: human report, JSON shape, --check gate (pass + fail), and --max-files routing.
• Full suite green: npm test → 1115 passing; typecheck + lint + build clean.

🤖 Generated with Claude Code