This commit addresses the Ubuntu installation issues reported in issue 380:
**PAM Module Fix:** - Fix .npmignore to include authenticate-pam module in npm package - Previously node_modules/ exclusion prevented
authenticate-pam from being packaged - Resolves \"PAM Authentication Warning: The native authenticate-pam module isn't found\"
**npm_config_prefix Conflict Detection:** - Add detection for npm_config_prefix conflicts with NVM in postinstall script - Warn users when
npm_config_prefix overrides NVM's per-version configuration - Provide clear instructions to resolve the conflict - Document
troubleshooting steps in docs/npm.md
