Moved primary lcd and navigation into dedicated files

src/navigation/input.rs

@@ -1 +1,15 @@
-// Navigation input module
+use esp_hal::gpio::{Input, InputConfig, Pull};
+use esp_hal::peripherals::GPIO38;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum NavCommand {
+    NextCard,
+    PrevCard,
+    Select,
+    ScanTag,
+}
+
+pub fn init_navigation_button(pin: GPIO38<'static>) -> Input<'static> {
+    let button_config = InputConfig::default().with_pull(Pull::Up);
+    Input::new(pin, button_config)
+}

src/navigation/state.rs

@@ -1 +1,35 @@
-// Navigation state module
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ScreenMode {
+    CardDetail,
+    DexGrid,
+    Settings,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct NavigationState {
+    pub current_screen: ScreenMode,
+    pub card_index: usize,
+    pub use_first_payload: bool,
+}
+
+impl Default for NavigationState {
+    fn default() -> Self {
+        Self {
+            current_screen: ScreenMode::CardDetail,
+            card_index: 0,
+            use_first_payload: true,
+        }
+    }
+}
+
+impl NavigationState {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn toggle_payload(&mut self) -> bool {
+        let current = self.use_first_payload;
+        self.use_first_payload = !self.use_first_payload;
+        current
+    }
+}