Add comprehensive UI system with action bar, unit frame, and character sheet

- Created UI system in level/ui/ folder
  - Action bar with 12 ability slots (Attack, Block, Dash, Jump + 8 expansion slots)
  - Unit frame showing player portrait with health bar
  - Character sheet/spellbook (toggle with Tab) displaying stats, weapons, and abilities
  - Tab hint indicator showing how to open character sheet
  - Custom theme with golden borders and dark backgrounds

- UI Components:
  - HUD Manager autoload handles all UI initialization and player connections
  - Ability buttons with cooldown overlay and keybind display
  - Real-time health and cooldown tracking via signals
  - Scrollable character sheet with two-page layout

- Player Integration:
  - Added UI signals: dash_cooldown_updated, attack_cooldown_updated, weapon_equipped_changed
  - Mouse capture system (Escape to toggle, click to recapture)
  - Synced attack cooldown from weapons to player for UI tracking

- Updated level.gd to connect local player to HUD Manager
- Updated CLAUDE.md with git commit guidelines

project.godot

@@ -20,6 +20,7 @@ config/icon="res://icon.png"
 [autoload]
 
 Network="*res://level/scripts/network.gd"
+HUD="*res://level/ui/scripts/hud_manager.gd"
 
 [display]
 
@@ -88,6 +89,11 @@ block={
 "events": [Object(InputEventMouseButton,"resource_local_to_scene":false,"resource_name":"","device":-1,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"button_mask":2,"position":Vector2(0, 0),"global_position":Vector2(0, 0),"factor":1.0,"button_index":2,"canceled":false,"pressed":true,"double_click":false,"script":null)
 ]
 }
+toggle_character_sheet={
+"deadzone": 0.5,
+"events": [Object(InputEventKey,"resource_local_to_scene":false,"resource_name":"","device":-1,"window_id":0,"alt_pressed":false,"shift_pressed":false,"ctrl_pressed":false,"meta_pressed":false,"pressed":false,"keycode":0,"physical_keycode":4194306,"key_label":0,"unicode":0,"location":0,"echo":false,"script":null)
+]
+}
 
 [layer_names]