tui: F5 thalamus screen, fix HashMap ordering, Screen enum

- Add Thalamus variant to Screen enum (F5)
- Fix HashMap iteration ordering causing flickering in F4/F5
  screens by using BTreeMap in supervisor and sorting plan_counts
- Update screen legend: F1=interact F2=conscious F3=subconscious
  F4=unconscious F5=thalamus
- Add dirty bit field to App (prep for event-driven rendering)

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

src/user/tui/mod.rs

@@ -21,7 +21,7 @@ mod subconscious_screen;
 mod unconscious_screen;
 mod thalamus_screen;
 
-pub(crate) const SCREEN_LEGEND: &str = " F1=interact  F2=conscious  F3=subconscious  F4=unconscious ";
+pub(crate) const SCREEN_LEGEND: &str = " F1=interact  F2=conscious  F3=subconscious  F4=unconscious  F5=thalamus ";
 /// Subconscious agents — interact with conscious context
 pub(crate) const SUBCONSCIOUS_AGENTS: &[&str] = &["surface-observe", "journal", "reflect"];
 /// Unconscious agents — background consolidation
@@ -380,6 +380,8 @@ pub(crate) enum Screen {
     Subconscious,
     /// F4 — memory daemon status
     Unconscious,
+    /// F5 — thalamus: channels, presence, attention routing
+    Thalamus,
 }
 
 /// Actions triggered by hotkeys, consumed by the main loop.
@@ -577,6 +579,7 @@ impl App {
             KeyCode::F(2) => { self.set_screen(Screen::Conscious); return; }
             KeyCode::F(3) => { self.set_screen(Screen::Subconscious); return; }
             KeyCode::F(4) => { self.set_screen(Screen::Unconscious); return; }
+            KeyCode::F(5) => { self.set_screen(Screen::Thalamus); return; }
             _ => {}
         }
 
@@ -677,7 +680,7 @@ impl App {
                     _ => {}
                 }
             }
-            Screen::Unconscious => {
+            Screen::Unconscious | Screen::Thalamus => {
                 match key.code {
                     KeyCode::PageUp => { self.debug_scroll = self.debug_scroll.saturating_sub(10); return; }
                     KeyCode::PageDown => { self.debug_scroll += 10; return; }
@@ -815,6 +818,7 @@ impl App {
             Screen::Conscious => { self.draw_debug(frame, size); return; }
             Screen::Subconscious => { self.draw_agents(frame, size); return; }
             Screen::Unconscious => { self.draw_unconscious(frame, size); return; }
+            Screen::Thalamus => { self.draw_thalamus(frame, size); return; }
             Screen::Interact => {}
         }