Automate changelog/releases and add OSS repo standards

[akshaymagapu]

Summary

• Add release-please workflow for automated versioning and changelog PRs.
• Switch npm publish workflow to release-triggered publishing with npm auth precheck.
• Add standard OSS repo files:
  • Issue templates
  • PR template
  • CODEOWNERS
  • Dependabot config
  • CHANGELOG.md

Why

• Keep versioning and changelog generation consistent.
• Reduce manual release steps and publishing mistakes.
• Improve contributor workflow and repository maintenance.

Validation

• Local checks passed: npm run ci

Attribution

Co-created with Codex.