plans: rename resident agent Hermes -> Nomos, add implementable rename phase N0

Nomos (from oikonomos, steward of the oikos) avoids the name collision
with Nous Research's Hermes Agent. N0 enumerates the full rename scope:
cmd/, hermes/ dir, env vars, config fields, compose service, Caddy vhost,
identity-preserving DB slug migration + seed update, persona docs.
History, the Matrix bot user, and legacy bin/hermes stay untouched.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

plans/index.md

@@ -12,7 +12,7 @@ went sideways, open an investigation.
 | 2026-07-08 | [Plan vs implementation cross-reference](2026-07-08-plan-implementation-audit.md) | Planned |
 | 2026-07-08 | [Oikos gaps, broken things, and improvements](2026-07-08-oikos-gaps-and-improvements.md) | Planned |
 | 2026-07-08 | [Control room web UI](2026-07-08-control-room-webui.md) | Planned |
-| 2026-07-08 | [Hermes resident agent](2026-07-08-hermes-resident-agent.md) | Planned |
+| 2026-07-08 | [Nomos resident agent (renames Hermes)](2026-07-08-nomos-resident-agent.md) | Planned |
 
 ## Done