broker: fix direct-run detection for symlinked release path

[benvinegar]

Summary

• fix bin/broker-register.mjs main-module detection when invoked via symlinked release path (/opt/baudbot/current/...)
• add isMainModule() helper that compares resolved and realpath URLs
• add test coverage for symlink argv path handling

Why

sudo baudbot broker register could exit silently with code 0 because module URL and argv path differed across /opt/baudbot/current symlink boundaries.

Validation

• node --check bin/broker-register.mjs
• node --test bin/broker-register.test.mjs

[greptile-apps]

Greptile Summary

Fixed silent exit bug when broker-register.mjs is invoked via symlinked release path (e.g., /opt/baudbot/current/bin/broker-register.mjs → /opt/baudbot/releases/<sha>/bin/broker-register.mjs).

Changes:

• Added isMainModule() helper that compares both resolved path and realpath to handle symlinks correctly
• Replaced hardcoded main-module check with the new helper function
• Added comprehensive test coverage for symlink argv path handling

Why this matters:
The deployment architecture uses symlinks (current → releases/<sha>) for atomic release switches. The old check (import.meta.url === file://${process.argv[1]}) would fail when the script was invoked via a symlink because import.meta.url resolves to the real file path while process.argv[1] stays as the symlink path, causing the script to exit silently without executing.

Confidence Score: 5/5

• This PR is safe to merge with no identified risks
• The fix is well-contained, solves a real production issue with symlinked paths, includes proper error handling with try-catch blocks, and has comprehensive test coverage validating the new behavior
• No files require special attention

Important Files Changed

Filename	Overview
bin/broker-register.mjs	Added isMainModule() helper to handle symlinked paths by comparing both resolved and realpath URLs, fixing silent exit issue when script is invoked via symlink
bin/broker-register.test.mjs	Added test coverage for isMainModule() symlink handling using temporary files and symlink creation

_{Last reviewed commit: 15a8c88}