feat: add export and import functionality for snippets with UI controls

src/StorageManager.js

@@ -13,4 +13,31 @@ export class StorageManager {
     saveSnippets(snippets) {
         localStorage.setItem(this.SNIPPETS_KEY, JSON.stringify(snippets));
     }
+
+    exportSnippets() {
+        const snippets = this.loadSnippets();
+        const blob = new Blob([JSON.stringify(snippets, null, 2)], { type: 'application/json' });
+        const url = URL.createObjectURL(blob);
+        const a = document.createElement('a');
+        a.href = url;
+        a.download = 'astrolabe-snippets.json';
+        document.body.appendChild(a);
+        a.click();
+        document.body.removeChild(a);
+        URL.revokeObjectURL(url);
+    }
+
+    async importSnippets(file) {
+        try {
+            const text = await file.text();
+            const snippets = JSON.parse(text);
+            if (!Array.isArray(snippets)) {
+                throw new Error('Invalid snippets format');
+            }
+            this.saveSnippets(snippets);
+            return snippets;
+        } catch (err) {
+            throw new Error('Failed to import snippets: ' + err.message);
+        }
+    }
 }