P4: persona noun — Agent + ToRunnable bridge + Memory store

The headline P4 piece (clean redesign): the Agent persona noun, decoupled from
its Discord shell.
- agent.go/storage.go/builtin_loader.go moved from mort's pkg/logic/agents; the
  Storage seam drops the Discord CommandBindingStorage embedding (a host
  concern). The host-entangled files (commands, chatbot_provider, command-
  binding dispatcher, personalization, system) stay in mort.
- runnable.go: Agent.ToRunnable() lowers a persona into run.RunnableAgent — the
  bridge that lets run.Executor run a persona without importing this battery
  (the inversion of agentexec.Run(*agents.Agent)).
- memory.go: NewMemory() — zero-dep in-process persona Storage (all 11 CRUD +
  trigger-query methods).

Tests: ToRunnable field/phase mapping; Memory round-trip. CI invariant: core
imports ZERO from persona.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -68,7 +68,9 @@ CORE (majordomo + stdlib):
             web/net/compose groups + default backends     [P3]
 
 BATTERIES (opt-in siblings, each nil-safe + a default):
-  persona/   Agent noun + AgentStore seam + yml loader   [P4]
+  persona/   Agent noun + Storage seam + builtin loader [P4 ~]
+             + ToRunnable() bridge to run.RunnableAgent +
+             Memory default (host: chatbot/commands/personalization)
   skill/     rich Skill + SkillStore seam + toml loader  [P4]
   audit/     run.Audit Sink + Writer + queryable Memory  [P4 ✓]
              default (skillaudit Storage iface; GORM stays in mort)