fix(ios): surface block inserter media failures to the user

[dcalhoun]

What?

Media import failures in the native block inserter showed the user nothing at all. BlockInserterViewModel.error was assigned but never read by any view, so a failed photo import or camera capture left the inserter sheet open with no feedback.

Why?

The lack of user feedback during causes confusion.

How?

Bind error to an .alert(item:) in BlockInserterView — MediaError is already Identifiable.

Replace the system-derived messages with a small set of localized strings. Previously the picker path surfaced error.localizedDescription, which for the common URLError.unknown case is generic text that tells a user nothing actionable, and the camera path threw an unlocalized "Failed to convert image to JPEG" literal. Three new EditorLocalization cases: one shared alert title, one message per failure family, plus ok. Hosts that do not translate them fall back to the editor's own strings and get a one-time log, per the existing design.

Testing Instructions

Neither failure is easy to trigger organically — the picker path realistically needs an offloaded iCloud photo with no network, and the camera path needs a device. Apply the patch below to force both.

Reproduction patch — forces both failures

Both failures fire from independent entry points, so this triggers each one without toggling anything: the photo button demonstrates one message, the camera button the other.

diff --git a/ios/Sources/GutenbergKit/Sources/Views/BlockInserter/BlockInserterView.swift b/ios/Sources/GutenbergKit/Sources/Views/BlockInserter/BlockInserterView.swift
--- a/ios/Sources/GutenbergKit/Sources/Views/BlockInserter/BlockInserterView.swift
+++ b/ios/Sources/GutenbergKit/Sources/Views/BlockInserter/BlockInserterView.swift
@@ -179,7 +179,10 @@ struct BlockInserterView: View {
             }
 
             Button {
-                isShowingCamera = true
+                // TEMPORARY: route straight to `processCameraMedia` so the
+                // captured-media alert is reachable in the Simulator, which
+                // has no camera.
+                insertCameraMedia(.photo(UIImage()))
             } label: {
                 Image(systemName: "camera")
             }
diff --git a/ios/Sources/GutenbergKit/Sources/Views/BlockInserter/BlockInserterViewModel.swift b/ios/Sources/GutenbergKit/Sources/Views/BlockInserter/BlockInserterViewModel.swift
--- a/ios/Sources/GutenbergKit/Sources/Views/BlockInserter/BlockInserterViewModel.swift
+++ b/ios/Sources/GutenbergKit/Sources/Views/BlockInserter/BlockInserterViewModel.swift
@@ -77,6 +77,7 @@ class BlockInserterViewModel: ObservableObject {
             var anyError: Error?
 
             do {
+                throw URLError(.unknown) // TEMPORARY: force picker failure.
                 for item in items {
                     let item = try await self.fileManager.import(item)
                     results.append(item)
@@ -108,6 +109,9 @@ class BlockInserterViewModel: ObservableObject {
             do {
                 let mediaInfo: MediaInfo
 
+                // TEMPORARY: force camera failure.
+                throw MediaError(message: EditorLocalization[.failedToProcessCapturedMedia])
+
                 switch media {
                 case .photo(let image):
                     guard let imageData = image.jpegData(compressionQuality: 0.8) else {

This produces two code after 'throw' will never be executed warnings. Expected — wrapping each throw in if true { } silences them if you prefer a clean build.

With the patch applied, in the Demo app:

1. Open a post and tap + to open the block inserter.
2. Tap the photo toolbar button and select any image. Expected: an alert titled "Failed to insert media" with "The selected media could not be loaded. It may not be fully downloaded to this device."
3. Dismiss, then select an image via the inline picker under "Most used" and tap the +N confirm button. Expected: the same alert.
4. Tap the camera toolbar button. Expected: an alert titled "Failed to insert media" with "The captured media could not be processed."
5. Confirm the alert renders correctly over the still-presented inserter sheet, and that dismissing it leaves the inserter usable.

Then revert the patch and confirm the regression path:

6. Insert a photo normally. Expected: it inserts as before, with no alert.

Accessibility Testing Instructions

With VoiceOver enabled, follow the steps above. On failure, VoiceOver should announce the alert title and message, and focus should move into the alert. Confirm the OK button is reachable and dismisses it, returning focus to the inserter.

Screenshots or screencast

Media strip	Camera

[wpmobilebot]

XCFramework Build

This PR's XCFramework is available for testing. Add the following to your Package.swift:

.package(url: "https://github.com/wordpress-mobile/GutenbergKit", branch: "pr-build/598")

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