feat: add npm package distribution (Issue #123)

[vmvarela]

Summary

Closes #123

Changes

• New packaging files (packaging/npm/):

  • package.json — metadata, bin entry, files array, engines (node >=18)
  • bin/sql-pipe.js — platform/arch detecting launcher for 6 targets
  • .npmignore — whitelists only bin/, package.json, LICENSE

• CI workflow (.github/workflows/release.yml):

  • Added publish-npm job with Trusted Publishing (OIDC)
  • Runs after release job, needs id-token: write permission
  • Stages 6 binaries, copies packaging files, sets version, publishes with provenance
  • Graceful skip if OIDC not configured (continue-on-error: true)

• Documentation (README.md):

  • Added npm install section to Quick Start

Manual First Publish (Completed)

• Published @vmvarela/sql-pipe@0.24.0 to npm registry
• Verified npm install -g @vmvarela/sql-pipe works correctly

Next Steps (Required for Automated CI Publishes)

Configure Trusted Publishing on npmjs.com:

1. Go to: https://www.npmjs.com/settings/@vmvarela/packages/sql-pipe/publish
2. Add Trusted Publisher:
   • GitHub repo: vmvarela/sql-pipe
   • Workflow: release.yml
   • Environment: (leave blank or "release")

Acceptance Criteria

• packaging/npm/package.json created with correct metadata
• packaging/npm/bin/sql-pipe.js launcher detects platform/arch
• Pre-built binaries for all 6 supported platforms staged by CI
• npm install -g @vmvarela/sql-pipe installs working CLI
• CI publish-npm job added with Trusted Publishing (OIDC)
• Job is no-op if Trusted Publishing not configured
• npm package version matches git tag version
• Installation instructions added to README.md