merge: integrate upstream RPG attributes customization system

Merged commits from upstream/main (d870731):
- Add customizable RPG attributes (STR/DEX/etc) with add/remove/rename
- Fix character stats editing (0% display bug, missing Stats line creation)
- Add mobile font-size overrides for better readability
- Fix together mode rendering order (render panels before cleaning DOM)
- Fix temperature unit toggle (C/F) and thermometer thresholds
- Add buildAttributesString() for custom attribute names in AI prompts

Upstream Features:
- trackerConfig.rpgAttributes array replaces showRPGAttributes boolean
- Per-attribute enable/disable, custom names, reordering
- Tracker editor UI for managing attributes
- Custom attribute names appear in AI prompts and dice rolls
- Backward compatible migration from old boolean toggle

Merge Conflict Resolution:
- src/systems/integration/sillytavern.js:
  * Kept both: upstream's "render before DOM cleaning" + our refreshDashboard()
  * Result: render panels → refresh dashboard → update DOM
- style.css:
  * Kept both: our Widget Integration CSS + upstream's Mobile Font Overrides
  * Our Recent Events width fix (width: 100%) preserved

Related upstream commits:
- d870731: Add customizable RPG attributes and fix character stats editing
- f20710f: Make RPG attributes customizable and editable
- 883212b: Add comprehensive mobile font-size overrides
- 718696e: Fix multiple UI and functionality issues

No functional changes to v2 dashboard yet - integration in next commit.

src/core/state.js

@@ -71,8 +71,16 @@ export let extensionSettings = {
                 { id: 'hygiene', name: 'Hygiene', enabled: true },
                 { id: 'arousal', name: 'Arousal', enabled: true }
             ],
-            // RPG Attributes toggle
+            // RPG Attributes (customizable D&D-style attributes)
             showRPGAttributes: true,
+            rpgAttributes: [
+                { id: 'str', name: 'STR', enabled: true },
+                { id: 'dex', name: 'DEX', enabled: true },
+                { id: 'con', name: 'CON', enabled: true },
+                { id: 'int', name: 'INT', enabled: true },
+                { id: 'wis', name: 'WIS', enabled: true },
+                { id: 'cha', name: 'CHA', enabled: true }
+            ],
             // Status section config
             statusSection: {
                 enabled: true,