Implement Elf Ranged Combat and Pinned Mechanic

- Added 'Shoot Bow' action for Elf with Ballistic Skill mechanics (1995 rules).
- Implemented strict Line of Sight (LOS) raycasting (Amanatides & Woo) with UI feedback for blockers.
- Added 'Pinned' status: Heroes adjacent to monsters (without intervening walls) cannot move.
- Enhanced UI with visual indicators for blocked shots (red circles) and temporary modals.
- Polished 'End Phase' button layout and hidden it during Monster phase.

src/engine/data/Heroes.js

@@ -38,6 +38,7 @@ export const HERO_DEFINITIONS = {
         stats: {
             move: 4,
             ws: 4,
+            bs: 4, // Added for Bow
             to_hit_missile: 4, // 4+ to hit with ranged
             str: 3,
             toughness: 3,