Make watchdog find Homebrew runtimes

[rtyer]

Summary

Add the standard Apple Silicon and Intel Homebrew binary directories to the watchdog PATH while preserving the caller-provided PATH.

Problem

Cron uses a minimal PATH on macOS. After daemon startup pre-flight checks were introduced, watchdog recovery failed when the configured runtime was installed by Homebrew, such as Codex at /opt/homebrew/bin/codex.

Verification

• bash -n scripts/watchdog.sh
• ran the watchdog under an empty cron-like environment
• ran goated doctor with the resulting minimal PATH; all eight checks passed
• confirmed cron automatically started one daemon after the prior daemon stopped

[alan-botts]

Thank you—this passed my focused review and is included in the reviewed 0.2.0 integration release: #40. I could not execute the final org merge because the available GitHub/deploy-key identity has no Endgame-Labs merge permission; #40 is ready for an authorized maintainer to merge.