feat: add reset button positions to settings

PROBLEM:
- Existing users with saved off-screen FAB positions can't see buttons
- No way to reset positions without clearing all extension settings
- Salixfire and other users on Xiaomi/other devices need safe positions

SOLUTION:
Added "Reset Button Positions" button in Advanced settings section

IMPLEMENTATION:

1. template.html (lines 241-249):
   - Added reset button in Advanced section after Clear Cache button
   - Blue-styled button with rotate icon
   - Help text explains it resets FAB positions to top-left

2. index.js (lines 361-390):
   - Added click handler for reset button
   - Resets all 3 FAB positions to safe top-left defaults:
     * Mobile toggle: top + 20px, left: 12px
     * Refresh: top + 80px, left: 12px
     * Debug: top + 140px, left: 12px
   - Saves settings immediately
   - Applies CSS positions to visible buttons (no page refresh needed)
   - Shows success toast notification

3. style.css (lines 2057-2083, 4123-4125):
   - Added .rpg-btn-reset-fab styles matching clear cache pattern
   - Blue color scheme (vs red for destructive clear cache)
   - Same sizing, padding, transitions as other buttons
   - Mobile responsive font-size with clamp()

USAGE:
Users experiencing off-screen buttons can now:
1. Open RPG Companion settings (gear icon)
2. Scroll to Advanced section
3. Click "Reset Button Positions"
4. All FAB buttons instantly move to safe top-left positions

This fixes the issue for Salixfire and any other users who:
- Have buttons saved in off-screen positions
- Can't scroll to find buttons
- Need to reset without clearing all settings

Works immediately without page refresh or extension reload.

style.css

@@ -2054,6 +2054,34 @@ body:has(.rpg-panel.rpg-position-left) #sheld {
     transform: translateY(0);
 }
 
+.rpg-btn-reset-fab {
+    width: 100%;
+    padding: 0.625em;
+    background: rgba(52, 152, 219, 0.2);
+    border: 2px solid rgba(52, 152, 219, 0.5);
+    border-radius: 0.5em;
+    color: #5dade2;
+    font-size: 1.2vw;
+    font-weight: 600;
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    gap: 0.5em;
+    transition: all 0.3s ease;
+}
+
+.rpg-btn-reset-fab:hover {
+    background: rgba(52, 152, 219, 0.3);
+    border-color: rgba(52, 152, 219, 0.8);
+    color: #85c1e9;
+    transform: translateY(-0.062rem);
+}
+
+.rpg-btn-reset-fab:active {
+    transform: translateY(0);
+}
+
 /* ============================================
    THEME VARIATIONS
    ============================================ */
@@ -4091,6 +4119,10 @@ body:has(.rpg-panel.rpg-position-left) #sheld {
     .rpg-btn-clear-cache {
         font-size: clamp(13px, 3.3vw, 17px) !important;
     }
+
+    .rpg-btn-reset-fab {
+        font-size: clamp(13px, 3.3vw, 17px) !important;
+    }
 }
 
 /* Very narrow screens - single column layout for all stats */