fix(skills): remove malformed nested code fences in browser-extension-builder (#338)

skills/browser-extension-builder/SKILL.md

@@ -34,9 +34,6 @@ Structure for modern browser extensions
 
 **When to use**: When starting a new extension
 
-```javascript
-## Extension Architecture
-
 ### Project Structure
 ```
 extension/
@@ -91,7 +88,6 @@ Popup ←→ Background (Service Worker) ←→ Content Script
               ↓
         chrome.storage
 ```
-```
 
 ### Content Scripts
 
@@ -99,9 +95,6 @@ Code that runs on web pages
 
 **When to use**: When modifying or reading page content
 
-```javascript
-## Content Scripts
-
 ### Basic Content Script
 ```javascript
 // content.js - Runs on every matched page
@@ -159,7 +152,6 @@ injectUI();
   }]
 }
 ```
-```
 
 ### Storage and State
 
@@ -167,9 +159,6 @@ Persisting extension data
 
 **When to use**: When saving user settings or data
 
-```javascript
-## Storage and State
-
 ### Chrome Storage API
 ```javascript
 // Save data
@@ -218,7 +207,6 @@ async function setStorage(data) {
 const { settings } = await getStorage(['settings']);
 await setStorage({ settings: { ...settings, theme: 'dark' } });
 ```
-```
 
 ## Anti-Patterns