Add customizable RPG attributes and fix character stats editing

Features:
- Made RPG attributes (STR/DEX/CON/INT/WIS/CHA) fully customizable
- Added enable/disable toggle for entire RPG Attributes section
- Users can add/remove/rename/toggle individual attributes
- Custom attribute names now appear in AI prompts for dice rolls
- Added proper CSS styling for attribute editor fields

Bug Fixes:
- Fixed character stat editing showing 0% on blur but saving correctly
- Character stats now create Stats line if missing from AI response
- Separated stat name from editable percentage value
- Added value sanitization (removes %, validates 0-100 range)
- Stats line now inserts before Thoughts line when created

Technical:
- Added buildAttributesString() helper in promptBuilder.js
- Updated generateTrackerInstructions and generateContextualSummary
- Restructured character stat HTML to prevent nested contenteditable
- Enhanced updateCharacterField to handle missing Stats lines
- Removed legacy default preset/regex import code

style.css

@@ -3682,6 +3682,36 @@ body:has(.rpg-panel.rpg-position-left) #sheld {
     opacity: 0.8;
 }
 
+/* RPG Attributes editor styles (same as custom stats) */
+.rpg-attr-toggle {
+    flex-shrink: 0;
+}
+
+.rpg-attr-name {
+    flex: 1;
+    padding: 0.375em 0.5em;
+    background: var(--rpg-bg);
+    border: 1px solid var(--rpg-border);
+    border-radius: 0.25em;
+    color: var(--rpg-text);
+    font-size: 0.95em;
+}
+
+.rpg-attr-remove {
+    flex-shrink: 0;
+    padding: 0.375em 0.625em;
+    background: var(--rpg-highlight);
+    border: none;
+    border-radius: 0.25em;
+    color: white;
+    cursor: pointer;
+    transition: opacity 0.2s;
+}
+
+.rpg-attr-remove:hover {
+    opacity: 0.8;
+}
+
 /* Toggle rows */
 .rpg-editor-toggle-row {
     display: flex;