Fix duplicate media import bug and rename MediaSidebar to MediaManager

- Renamed src/MediaSidebar.html to src/MediaManager.html to align with modal UI.
- Fixed race condition in Photo Picker polling preventing duplicate imports.
- Updated global.ts, initMenu.ts, and mediaHandlers.ts used in the fix.
- Fixed unit tests for mediaHandlers.

src/initMenu.ts

@@ -6,7 +6,7 @@ import { reinstallTriggers, installSalesSyncTrigger } from "./triggers"
 import { reconcileSalesHandler } from "./salesSync"
 import { toastAndLog } from "./sheetUtils"
 import { showSidebar } from "./sidebar"
-import { showMediaSidebar, debugScopes } from "./mediaHandlers"
+import { showMediaManager, debugScopes } from "./mediaHandlers"
 import { runSystemDiagnostics } from "./verificationSuite"
 
 export function initMenu() {
@@ -18,7 +18,7 @@ export function initMenu() {
         .addItem("Fill out product from template", fillProductFromTemplate.name)
         .addItem("Match product to Shopify", matchProductToShopifyHandler.name)
         .addItem("Update Shopify Product", updateShopifyProductHandler.name)
-        .addItem("Media Manager", showMediaSidebar.name)
+        .addItem("Media Manager", showMediaManager.name)
     )
     .addSeparator()
     .addSubMenu(