feat: v6.3.0 pipeline hardening — auth/authz bug-class, pr-monitoring pattern, completion trust-boundary, hook stdout-JSON discipline, reminder dedup (#41/#58/#59/#60/#61)

feat: v6.3.0 pipeline hardening — auth/authz bug-class, pr-monitoring pattern, completion trust-boundary, hook stdout-JSON discipline, reminder dedup (#41/#58/#59/#60/#61) #4