feat: add My Scripts/Team Scripts tabs and Build button to Script Library

- Add language field to ScriptTemplateListItem frontend type
- Add mine/shared params to scriptsApi.getTemplates
- Update scriptGeneratorStore.loadTemplates to accept filter params
- Reorganize ScriptLibraryPage with tab bar (My Scripts / Team Scripts)
- Add "Build a New Script" button linking to /script-builder

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/api/scripts.ts

@@ -20,6 +20,8 @@ export const scriptsApi = {
     category_slug?: string
     search?: string
     tags?: string // Phase 3: comma-separated tag filter
+    mine?: boolean
+    shared?: boolean
   }): Promise<ScriptTemplateListItem[]> {
     const response = await apiClient.get<ScriptTemplateListItem[]>('/scripts/templates', { params })
     return response.data