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

level/ui/scenes/ability_button.tscn

@@ -0,0 +1,75 @@
+[gd_scene load_steps=4 format=3 uid="uid://cq7xyb8n4h6yk"]
+
+[ext_resource type="Script" path="res://level/ui/scripts/ability_button.gd" id="1_script"]
+[ext_resource type="Theme" uid="uid://dvsh7tuhulnfm" path="res://level/ui/theme/wow_style.tres" id="2_theme"]
+
+[sub_resource type="StyleBoxFlat" id="StyleBoxFlat_panel"]
+bg_color = Color(0.15, 0.15, 0.15, 0.9)
+border_width_left = 2
+border_width_top = 2
+border_width_right = 2
+border_width_bottom = 2
+border_color = Color(0.6, 0.5, 0.2, 1)
+corner_radius_top_left = 4
+corner_radius_top_right = 4
+corner_radius_bottom_right = 4
+corner_radius_bottom_left = 4
+
+[node name="AbilityButton" type="PanelContainer"]
+custom_minimum_size = Vector2(64, 64)
+theme = ExtResource("2_theme")
+theme_override_styles/panel = SubResource("StyleBoxFlat_panel")
+script = ExtResource("1_script")
+
+[node name="MarginContainer" type="MarginContainer" parent="."]
+layout_mode = 2
+theme_override_constants/margin_left = 4
+theme_override_constants/margin_top = 4
+theme_override_constants/margin_right = 4
+theme_override_constants/margin_bottom = 4
+
+[node name="VBoxContainer" type="VBoxContainer" parent="MarginContainer"]
+layout_mode = 2
+
+[node name="Icon" type="TextureRect" parent="MarginContainer/VBoxContainer"]
+layout_mode = 2
+size_flags_vertical = 3
+expand_mode = 1
+stretch_mode = 5
+
+[node name="CooldownOverlay" type="ColorRect" parent="MarginContainer/VBoxContainer/Icon"]
+visible = false
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+color = Color(0, 0, 0, 0.7)
+
+[node name="CooldownLabel" type="Label" parent="MarginContainer/VBoxContainer/Icon"]
+visible = false
+layout_mode = 1
+anchors_preset = 8
+anchor_left = 0.5
+anchor_top = 0.5
+anchor_right = 0.5
+anchor_bottom = 0.5
+offset_left = -20.0
+offset_top = -11.5
+offset_right = 20.0
+offset_bottom = 11.5
+grow_horizontal = 2
+grow_vertical = 2
+theme_override_font_sizes/font_size = 24
+text = "3"
+horizontal_alignment = 1
+vertical_alignment = 1
+
+[node name="KeybindLabel" type="Label" parent="MarginContainer/VBoxContainer"]
+layout_mode = 2
+theme_override_colors/font_outline_color = Color(0, 0, 0, 1)
+theme_override_constants/outline_size = 2
+theme_override_font_sizes/font_size = 14
+text = "1"
+horizontal_alignment = 1