docs(agents): park #298 + #178 Engine/HITL NO_HOLE

[AdamRickards]

Docs-only park update from current main (6e79b51).

• Adds get_snmp_config.read: SSH close-format (community_access empty vs MOPS) #298 get_snmp_config as Engine NO_HOLE: SSH gold parity would require merging the cached show snmp trap community into community_access and its four-link lookup chain; no Engine primitive supports that multi-command key merge, and ro would be invented because the trap output has no access token.
• Adds get_aca.read: SSH overlay remainder (timeout cleared; selected_memory/slots parity) #178 get_aca as HITL NO_HOLE: show config envm labels and slot layout have never been captured, no sidecar catalog entry sends that command, and Tier1 direct capture is not authorized.
• SNMP=0 stays with get_snmp_config: community_access mops keys=3 vs snmp 0 (parity) #231.
• Next step: get_snmp_config.read: SSH close-format (community_access empty vs MOPS) #298 parks Engine until HITL opens; get_aca.read: SSH overlay remainder (timeout cleared; selected_memory/slots parity) #178 reopens when a raw capture exists, then becomes a soft Schema candidate.

Related: #298
Related: #178