build: use secure npm package manager config

[lirantal]

Scaffolds a secure package manager config file for this repo, following the recommendations in https://github.com/lirantal/npm-security-best-practices.

• For npm repos: adds .npmrc (disables lifecycle scripts, blocks git sources, enforces a 30-day minimum release age).
• For pnpm repos: adds pnpm-workspace.yaml with minimumReleaseAge, trustPolicy, strictDepBuilds, and blockExoticSubdeps.

This PR was opened as part of a bulk security-hardening pass across my repos. If this overwrites a custom config that was intentional, please close and revisit manually.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.01%. Comparing base (09dabb4) to head (d49c057).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #213   +/-   ##
=======================================
  Coverage   98.01%   98.01%           
=======================================
  Files          13       13           
  Lines         404      404           
  Branches       96       96           
=======================================
  Hits          396      396           
  Misses          8        8           

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