fix(core): unify MAX_LENGTH for SimpleChoice

### core/embed/rust/src/ui/layout_caesar/component/input_methods/simple_choice.rs
@@ -9,8 +9,15 @@ use crate::ui::geometry::Rect;
 use crate::ui::shape::Renderer;
 
 // So that there is only one implementation, and not multiple generic ones
-// as would be via `const N: usize` generics.
-const MAX_LENGTH: usize = 5;
+// as would be via `const N: usize` generics. Callers must size their `Vec`
+// with this constant rather than repeating the literal.
+pub const MAX_LENGTH: usize = 6;
+
+/// `select_menu()` renders through `SimpleChoice`, handing it a list already
+/// bounded by `MAX_MENU_ITEMS`. Keep the capacity at or above that bound so
+/// raising `MAX_MENU_ITEMS` alone cannot stop this model from building.
+#[cfg(feature = "micropython")]
+const _: () = assert!(MAX_LENGTH >= crate::ui::ui_firmware::MAX_MENU_ITEMS);
 
 struct ChoiceFactorySimple {
     choices: Vec<TString<'static>, MAX_LENGTH>,

### core/embed/rust/src/ui/layout_caesar/component/mod.rs
@@ -57,7 +57,7 @@ pub use input_methods::{
     number_input::NumberInput,
     passphrase::PassphraseEntry,
     pin::PinEntry,
-    simple_choice::SimpleChoice,
+    simple_choice::{SimpleChoice, MAX_LENGTH as SIMPLE_CHOICE_MAX_LENGTH},
     wordlist::{WordlistEntry, WordlistType},
 };
 #[cfg(feature = "translations")]

### core/embed/rust/src/ui/layout_caesar/ui_firmware.rs
@@ -6,7 +6,7 @@ use super::component::{
     AddressDetails, ButtonActions, ButtonDetails, ButtonLayout, ButtonPage, ChoiceControls,
     CoinJoinProgress, ConfirmHomescreen, Flow, FlowPages, Frame, Homescreen, Lockscreen,
     NumberInput, Page, PassphraseEntry, PinEntry, Progress, ScrollableFrame, ShareWords, ShowMore,
-    SimpleChoice, WordlistEntry, WordlistType,
+    SimpleChoice, WordlistEntry, WordlistType, SIMPLE_CHOICE_MAX_LENGTH,
 };
 use super::{constant, fonts, theme, UICaesar};
 use crate::error::Error;
@@ -939,7 +939,7 @@ impl FirmwareUI for UICaesar {
         description: TString<'static>,
         words: [TString<'static>; MAX_WORD_QUIZ_ITEMS],
     ) -> Result<impl LayoutMaybeTrace, Error> {
-        let words: Vec<TString<'static>, 5> = Vec::from_iter(words);
+        let words: Vec<TString<'static>, SIMPLE_CHOICE_MAX_LENGTH> = Vec::from_iter(words);
         // Returning the index of the selected word, not the word itself
         let layout = RootComponent::new(
             Frame::new(
@@ -955,7 +955,7 @@ impl FirmwareUI for UICaesar {
 
     fn select_word_count(recovery_type: RecoveryType) -> Result<impl LayoutMaybeTrace, Error> {
         let title: TString = TR::word_count__title.into();
-        let choices: Vec<TString<'static>, 5> = {
+        let choices: Vec<TString<'static>, SIMPLE_CHOICE_MAX_LENGTH> = {
             let nums: &[&str] = if matches!(recovery_type, RecoveryType::UnlockRepeatedBackup) {
                 &["20", "33"]
             } else {

### core/embed/rust/src/ui/layout_delizia/component/vertical_menu.rs
@@ -320,6 +320,7 @@ pub const VERTICAL_MENU_ITEMS: usize = 6;
 /// `MAX_MENU_ITEMS`, pushing with `unwrap!`, which panics on overflow rather
 /// than returning an error. Keep the capacity at or above that bound so raising
 /// `MAX_MENU_ITEMS` alone cannot turn a rejected menu into a fatal error.
+#[cfg(feature = "micropython")]
 const _: () = assert!(VERTICAL_MENU_ITEMS >= crate::ui::ui_firmware::MAX_MENU_ITEMS);
 
 pub type VerticalMenuItems = Vec<VerticalMenuItem, VERTICAL_MENU_ITEMS>;

### core/embed/rust/src/ui/layout_eckhart/firmware/vertical_menu.rs
@@ -21,6 +21,7 @@ pub const SHORT_MENU_ITEMS: usize = 6;
 /// `MAX_MENU_ITEMS`, and `MenuItems::push` panics on overflow rather than
 /// returning an error. Keep the capacity at or above that bound so raising
 /// `MAX_MENU_ITEMS` alone cannot turn a rejected menu into a fatal error.
+#[cfg(feature = "micropython")]
 const _: () = assert!(SHORT_MENU_ITEMS >= crate::ui::ui_firmware::MAX_MENU_ITEMS);
 
 pub type LongMenuGc = GcBox<Vec<Button, LONG_MENU_ITEMS>>;