Refactor duplicated scene controller patterns into base class

[justinmadison]

Summary

Several patterns are duplicated across scene controller subclasses (foraging.gd, crafting_chain.gd, team_capture.gd) that should be refactored into base_scene_controller.gd.

Duplicated Patterns

1. _input() handler - SPACE (start/stop), R (reset), S (step) keyboard handling is identical in all 3 scene controllers
2. _process() → _update_metrics_ui() - All 3 call _update_metrics_ui() from _process(). Could be a virtual method called from base class
3. _reset_scene() pattern - All 3 call simulation_manager.reset_simulation() and reset_backend_decisions(). A _on_scene_reset() hook could standardize this
4. _complete_scene() / _print_final_metrics() - Nearly identical completion guard + stop simulation + print metrics pattern

Context

Identified during Issue #64 (crafting system) implementation. Kept as a separate issue to keep #64 focused on crafting functionality.

Acceptance Criteria

• _input() handler moved to SceneController base class
• _process() calls virtual _update_metrics_ui() from base class
• _reset_scene() standardized with base class hook
• _complete_scene() pattern consolidated
• Existing foraging scene still works correctly after refactor