Add enabled toggle to AutoAgent, simplify unconscious scheduling

- AutoAgent.enabled: universal toggle for any auto agent
- Subconscious: should_trigger checks auto.enabled
- Unconscious: simplified from consolidation-plan-driven budgets to
  simple loop with cooldown. Static agent list, max 2 concurrent.
- TUI: unconscious agents shown in F3 subconscious screen under
  separator, with enabled/running/runs display

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/agent/oneshot.rs

@@ -36,6 +36,7 @@ pub struct AutoAgent {
     pub steps: Vec<AutoStep>,
     pub current_phase: String,
     pub turn: usize,
+    pub enabled: bool,
 }
 
 /// Per-run conversation backend — wraps a forked agent.
@@ -107,6 +108,7 @@ impl AutoAgent {
             name, tools, steps,
             current_phase: String::new(),
             turn: 0,
+            enabled: true,
         }
     }