Refactor sbc into feature-first layout + domain-agnostic command system

Move command_system out of commands/ to sbc/command_system/, with its built-in
commands under command_system/commands/. Split heightmap into
heightmap/{commands,model,tests}.

Make command_system domain-agnostic: Context no longer holds per-domain manager
fields. Domain models self-register via an inventory ModelFactory and are
reached type-erased through ctx.model::<T>(); SBC builds the registry once and
fans history events over the models generically. commands_api no longer
re-exports any domain type.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: gajop

…c/sbc/commands/command_system/command.rs native/src/sbc/command_system/command.rsnative/src/sbc/commands/command_system/command.rs renamed to native/src/sbc/command_system/command.rs native/src/sbc/commands/command_system/command.rs renamed to native/src/sbc/command_system/command.rs

@@ -1,8 +1,8 @@
 use serde::Deserialize;
 
-use super::command::Command;
-use super::context::{CommandManagerIntent, Context};
-use super::registry::register_command;
+use super::super::command::Command;
+use super::super::context::{CommandManagerIntent, Context};
+use super::super::registry::register_command;
 
 #[derive(Deserialize)]
 pub struct ClearUndoRedoCommand;

…mmands/command_system/command_manager.rs …rc/sbc/command_system/command_manager.rsnative/src/sbc/commands/command_system/command_manager.rs renamed to native/src/sbc/command_system/command_manager.rs native/src/sbc/commands/command_system/command_manager.rs renamed to native/src/sbc/command_system/command_manager.rs

@@ -0,0 +1,4 @@
+mod clear_undo_redo_command;
+mod redo_command;
+mod set_multiple_command_mode_command;
+mod undo_command;

…ommand_system/clear_undo_redo_command.rs …stem/commands/clear_undo_redo_command.rsnative/src/sbc/commands/command_system/clear_undo_redo_command.rs renamed to native/src/sbc/command_system/commands/clear_undo_redo_command.rs native/src/sbc/commands/command_system/clear_undo_redo_command.rs renamed to native/src/sbc/command_system/commands/clear_undo_redo_command.rs

@@ -1,9 +1,9 @@
 use serde::Deserialize;
 
-use crate::sbc::commands::command_system::registry::register_command;
+use crate::sbc::command_system::registry::register_command;
 
-use super::command::Command;
-use super::context::{CommandManagerIntent, Context};
+use super::super::command::Command;
+use super::super::context::{CommandManagerIntent, Context};
 
 #[derive(Deserialize)]
 pub struct RedoCommand;

native/src/sbc/command_system/commands/mod.rs

@@ -1,8 +1,8 @@
 use serde::Deserialize;
 
-use super::command::Command;
-use super::context::{CommandManagerIntent, Context};
-use super::registry::register_command;
+use super::super::command::Command;
+use super::super::context::{CommandManagerIntent, Context};
+use super::super::registry::register_command;
 
 #[derive(Deserialize)]
 pub struct SetMultipleCommandModeCommand {

…/commands/command_system/redo_command.rs …/command_system/commands/redo_command.rsnative/src/sbc/commands/command_system/redo_command.rs renamed to native/src/sbc/command_system/commands/redo_command.rs native/src/sbc/commands/command_system/redo_command.rs renamed to native/src/sbc/command_system/commands/redo_command.rs

@@ -1,8 +1,8 @@
 use serde::Deserialize;
 
-use super::command::Command;
-use super::context::{CommandManagerIntent, Context};
-use super::registry::register_command;
+use super::super::command::Command;
+use super::super::context::{CommandManagerIntent, Context};
+use super::super::registry::register_command;
 
 #[derive(Deserialize)]
 pub struct UndoCommand;

…tem/set_multiple_command_mode_command.rs …nds/set_multiple_command_mode_command.rsnative/src/sbc/commands/command_system/set_multiple_command_mode_command.rs renamed to native/src/sbc/command_system/commands/set_multiple_command_mode_command.rs native/src/sbc/commands/command_system/set_multiple_command_mode_command.rs renamed to native/src/sbc/command_system/commands/set_multiple_command_mode_command.rs

@@ -0,0 +1,40 @@
+use spring_native::prelude::NativeInterfaceRef;
+
+use crate::sbc::command_system::command::CommandId;
+use crate::sbc::command_system::model::{Model, Models};
+
+/// A command's request back to the command manager, applied after `execute`
+/// returns so it doesn't re-enter the manager mid-call.
+pub enum CommandManagerIntent {
+    Undo,
+    Redo,
+    Clear,
+    SetMultipleCommandMode(bool),
+}
+
+pub struct Context<'a> {
+    pub interface: &'a NativeInterfaceRef,
+    pub current_command_id: CommandId,
+    pub command_manager_intents: Vec<CommandManagerIntent>,
+    models: &'a mut Models,
+}
+
+impl<'a> Context<'a> {
+    pub fn new(
+        interface: &'a NativeInterfaceRef,
+        command_id: CommandId,
+        models: &'a mut Models,
+    ) -> Self {
+        Context {
+            interface,
+            current_command_id: command_id,
+            command_manager_intents: Vec::new(),
+            models,
+        }
+    }
+
+    /// The domain model of type `T` (panics if no feature registered one).
+    pub fn model<T: Model>(&mut self) -> &mut T {
+        self.models.get::<T>()
+    }
+}