feat(media): implement integrated media manager with sidebar and picker

- Implement DriveService and ShopifyMediaService for backend operations
- Create MediaSidebar.html with premium UI and auto-polling
- Integrate Google Picker API for robust file selection
- Orchestrate sync logic via MediaService (Drive -> Staged Upload -> Shopify)
- Add secure config handling for API keys and tokens
- Update ppsscript.json with required OAuth scopes
- Update MEMORY.md and README.md with architecture details

src/services/ShopifyMediaService.ts

@@ -0,0 +1,71 @@
+import { IShopifyMediaService } from "../interfaces/IShopifyMediaService"
+import { IShop } from "../interfaces/IShop"
+import { formatGqlForJSON } from "../shopifyApi"
+
+export class ShopifyMediaService implements IShopifyMediaService {
+  private shop: IShop
+
+  constructor(shop: IShop) {
+    this.shop = shop
+  }
+
+  stagedUploadsCreate(input: any[]): any {
+    const query = /* GraphQL */ `
+      mutation stagedUploadsCreate($input: [StagedUploadInput!]!) {
+        stagedUploadsCreate(input: $input) {
+          stagedTargets {
+            url
+            resourceUrl
+            parameters {
+              name
+              value
+            }
+          }
+          userErrors {
+            field
+            message
+          }
+        }
+      }
+    `
+    const variables = { input }
+    const payload = {
+      query: formatGqlForJSON(query),
+      variables: variables
+    }
+    const response = this.shop.shopifyGraphQLAPI(payload)
+    return response.content.data.stagedUploadsCreate
+  }
+
+  productCreateMedia(productId: string, media: any[]): any {
+    const query = /* GraphQL */ `
+      mutation productCreateMedia($media: [CreateMediaInput!]!, $productId: ID!) {
+        productCreateMedia(media: $media, productId: $productId) {
+          media {
+            alt
+            mediaContentType
+            status
+          }
+          mediaUserErrors {
+            field
+            message
+          }
+          product {
+            id
+            title
+          }
+        }
+      }
+    `
+    const variables = {
+      productId,
+      media
+    }
+    const payload = {
+      query: formatGqlForJSON(query),
+      variables: variables
+    }
+    const response = this.shop.shopifyGraphQLAPI(payload)
+    return response.content.data.productCreateMedia
+  }
+}