feat: add privacy-bounded Devbox Insights

[vicotrbb]

Summary

• add opt-in, privacy-bounded Devboxes Insights for Codex/Claude telemetry and aggregate Git activity
• add durable SQLite storage, scoped workspace ingest credentials, outboxes, backups, retention, export, and purge
• add responsive dashboard, CLI metrics workflows, Helm contracts, documentation, and end-to-end lifecycle coverage
• prepare the repository for v0.3.0

Validation

• make lint
• make test (129 controller tests, 88.86% coverage; 17 CLI tests)
• make helm
• make images
• clean Kind lifecycle: ingest, dedupe, Git baseline/delta, CLI/dashboard APIs, backup, SSH/tmux, controller/workspace restart, retained PVC/history, recreate, and purge
• Gitleaks staged diff scan