fix: center icons in compact buttons with fixed dimensions and flexbox

Properly centered icons by wrapping text in spans and forcing exact button
dimensions to override base min-width: fit-content style.

Root Cause:
- Base .rpg-inventory-add-btn has min-width: fit-content
- Even with span hidden, button width wasn't constrained
- Icon appeared off-center with extra space to the right

Solution:

1. HTML Structure (inventoryWidget.js, questsWidget.js):
   - Wrapped text in <span class="rpg-btn-label">
   - Pattern: <i class="fa-solid fa-plus"></i><span class="rpg-btn-label"> Add Item</span>
   - Applied to: Add Item, Add Location, Add Asset, Add Quest buttons

2. CSS (style.css):
   - Hide labels: .rpg-inventory-compact .rpg-btn-label { display: none; }
   - Force square dimensions: width: 32px !important (overrides fit-content)
   - Center icon: display: inline-flex; justify-content: center; align-items: center
   - Remove padding: padding: 0 (icon uses full 32px space)

Result: Perfect 32×32px square buttons with centered icons in compact mode,
matching the pattern used for sub-tab buttons throughout the codebase.

Fixes: Icon skewed left in Add Item/Quest buttons at narrow widths

style.css

@@ -7698,15 +7698,19 @@ body:has(.rpg-panel.rpg-position-left) #sheld {
     gap: 0.5rem; /* Reduced from 0.75rem */
 }
 
-.rpg-inventory-compact .rpg-inventory-add-btn {
-    font-size: 0; /* Hide text, show icon only */
-    padding: 0.4rem;
-    min-width: 32px;
-    min-height: 32px;
+.rpg-inventory-compact .rpg-btn-label {
+    display: none;
 }
 
-.rpg-inventory-compact .rpg-inventory-add-btn i {
-    font-size: 1rem; /* Restore icon size */
+.rpg-inventory-compact .rpg-inventory-add-btn {
+    padding: 0;
+    width: 32px !important; /* Override min-width: fit-content */
+    height: 32px;
+    min-width: 32px;
+    min-height: 32px;
+    display: inline-flex;
+    justify-content: center;
+    align-items: center;
 }
 
 .rpg-inventory-compact .rpg-view-toggle-btn {
@@ -7999,15 +8003,19 @@ body:has(.rpg-panel.rpg-position-left) #sheld {
     gap: 0.5rem; /* Reduced from default */
 }
 
-.rpg-quests-compact .rpg-add-quest-btn {
-    font-size: 0; /* Hide text, show icon only */
-    padding: 0.4rem;
-    min-width: 32px;
-    min-height: 32px;
+.rpg-quests-compact .rpg-btn-label {
+    display: none;
 }
 
-.rpg-quests-compact .rpg-add-quest-btn i {
-    font-size: 1rem; /* Restore icon size */
+.rpg-quests-compact .rpg-add-quest-btn {
+    padding: 0;
+    width: 32px !important; /* Override base button min-width */
+    height: 32px;
+    min-width: 32px;
+    min-height: 32px;
+    display: inline-flex;
+    justify-content: center;
+    align-items: center;
 }
 
 .rpg-quests-compact .rpg-quest-item {