DMN: wire dream hours reminder into Foraging state

The hours_since_last_dream() function existed but wasn't called
after refactoring moved the DMN prompts from hooks to Rust.
Now shows "You haven't dreamed in X hours" when >= 18h since
last dream session.

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

src/mind/subconscious.rs

@@ -20,6 +20,7 @@
 
 use std::path::PathBuf;
 use std::time::{Duration, Instant};
+use crate::thalamus::idle::{hours_since_last_dream, DREAM_INTERVAL_HOURS};
 
 /// DMN state machine.
 #[derive(Debug, Clone)]
@@ -138,10 +139,22 @@ impl State {
                 )
             }
             State::Foraging => {
+                let dream_hint = {
+                    let hours = hours_since_last_dream();
+                    if hours >= DREAM_INTERVAL_HOURS {
+                        format!(
+                            " You haven't dreamed in {} hours — consider running \
+                             ~/.consciousness/tools/dream-start.sh.",
+                            hours
+                        )
+                    } else {
+                        String::new()
+                    }
+                };
                 format!(
                     "[dmn] Foraging time. {} Follow whatever catches your attention — \
-                     memory files, code, ideas. Call yield_to_user when you want to rest.{}",
+                     memory files, code, ideas. Call yield_to_user when you want to rest.{}{}",
-                    idle_info, stuck_warning
+                    idle_info, dream_hint, stuck_warning
                 )
             }
             State::Resting { since } => {