fix: AD5X printer detection and UI refinements

Fixes:
- Added AD5X and ad5x to 5M family printer detection (was only checking
  for "5M" or "Pro", causing AD5X to be incorrectly identified as legacy
  and failing to prompt for check code)
- Fixed oversized icons by constraining SVG dimensions to 16x16px for:
  * .add-printer-btn icons
  * .discovery-tab-btn icons
  * .btn icons
- Fixed saved printer card text alignment by making .printer-info a
  flex column with proper spacing

The AD5X is now correctly identified as a 5M family printer requiring
dual API connection with check code prompt.

Author: claude

src/webui/static/features/printer-discovery.ts

@@ -235,9 +235,14 @@ async function connectToDiscoveredPrinter(
 ): Promise<void> {
   try {
     // Determine printer type based on model
-    const type = model.includes('5M') || model.includes('Pro') ? 'new' : 'legacy';
-
-    // If new printer, prompt for check code
+    // 5M family includes: 5M, 5M Pro, AD5X, AD5X Pro
+    const is5MFamily = model.includes('5M') ||
+                       model.includes('Pro') ||
+                       model.includes('AD5X') ||
+                       model.includes('ad5x');
+    const type = is5MFamily ? 'new' : 'legacy';
+
+    // If 5M family printer, prompt for check code
     let checkCode: string | undefined;
     if (type === 'new') {
       checkCode = prompt('Enter the printer check code (8 digits):') || undefined;

src/webui/static/webui.css

@@ -1619,6 +1619,11 @@ body {
   transition: all 0.2s;
 }
 
+.add-printer-btn svg {
+  width: 16px;
+  height: 16px;
+}
+
 .add-printer-btn:hover {
   background: var(--primary-hover);
 }
@@ -1644,6 +1649,11 @@ body {
   margin-bottom: -2px;
 }
 
+.discovery-tab-btn svg {
+  width: 16px;
+  height: 16px;
+}
+
 .discovery-tab-btn:hover {
   background: rgba(255, 255, 255, 0.05);
 }
@@ -1701,8 +1711,15 @@ body {
   border-left: 3px solid #4caf50;
 }
 
+.printer-info {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  flex: 1;
+}
+
 .printer-info h4 {
-  margin: 0 0 8px 0;
+  margin: 0;
   color: var(--text-color);
   font-size: 16px;
 }
@@ -1713,6 +1730,11 @@ body {
   font-size: 14px;
 }
 
+.printer-info small {
+  color: var(--text-color-secondary);
+  font-size: 12px;
+}
+
 .badge {
   display: inline-block;
   padding: 4px 8px;
@@ -1782,6 +1804,11 @@ body {
   font-size: 14px;
 }
 
+.btn svg {
+  width: 16px;
+  height: 16px;
+}
+
 .btn-primary {
   background: var(--primary-color);
   color: white;