feat(android): add photo-permission rationale and recent-photos strip

[jkmassel]

Summary

Layers on top of #509 with the photo-permission state machine, the rationale card, and the recent-photos thumbnail strip.

Three media-strip states resolved at runtime by resolveMediaStripView in PhotoAccessState.kt:

1. Rationale card — shown when READ_MEDIA_IMAGES isn't granted and the user hasn't dismissed it. Body copy and primary-button label swap across three sub-states (Unasked / Denied / PermanentlyDenied); SharedPreferences tracks the first-prompt flag because shouldShowRequestPermissionRationale alone can't tell "never asked" from "permanently denied".
2. Compact tiles — once the rationale is rejected, the Photos / Camera column flattens into a full-width 88dp row. The rejection auto-clears when permission is later granted via clearRejectedRationale, so a future revocation surfaces the rationale again instead of stranding the user in CompactTiles with no in-app affordance to re-engage.
3. Full strip — once granted, queries MediaStore for the 64 most recent images and renders them as a horizontally-scrolling 2-row thumbnail grid. LazyRow keeps off-screen thumbnails out of memory.

Lifecycle observer

The strip observes the host Activity's lifecycle (via LocalContext.findActivity() walking the ContextWrapper chain), not the BottomSheetDialog's own LifecycleRegistry. The dialog's lifecycle only dispatches ON_RESUME from show() and never refires when the user leaves to system Settings and returns; the Activity's does. This is what makes the "grant via Settings → strip updates on return" path work even when the inserter sheet stays open through the round-trip.

canReprompt state

Modelled as its own mutableStateOf, explicitly recomputed at every permission-relevant signal (launcher result, lifecycle resume) via the refreshAccessState helper. Compose's snapshot system can't see the OS-level shouldShowRequestPermissionRationale flip from true → false on the 2nd denial otherwise — granted and promptedBefore are already in their post-deny values, so neither would notify Compose and the rationale would stay stuck on "Try Again".

Manifest permissions

This PR adds two host-visible <uses-permission> declarations to the library manifest:

Permission	SDK range	Purpose
READ_MEDIA_IMAGES	33+	Read MediaStore images for the thumbnail strip.
READ_EXTERNAL_STORAGE	≤32	Pre-Android-13 fallback for the same read.

Android 14+'s three-option permission dialog ("Allow all" / "Select photos" / "Don't allow") is surfaced by the system whenever an app at targetSdk ≥ 34 requests READ_MEDIA_IMAGES, regardless of whether the manifest opts in to READ_MEDIA_VISUAL_USER_SELECTED (verified empirically on Pixel 9 Pro XL / Android 16). hasPhotosPermission checks both permissions, so a "Select photos" choice is treated as granted and MediaStore scopes the strip to the user-selected items. Declaring READ_MEDIA_VISUAL_USER_SELECTED in the library manifest to unlock the "Select more photos" re-prompt UX is #511.

Hosts that don't ship the media strip can opt out:

<uses-permission
    android:name="android.permission.READ_MEDIA_IMAGES"
    tools:node="remove" />
<uses-permission
    android:name="android.permission.READ_EXTERNAL_STORAGE"
    tools:node="remove" />

With the permissions removed, hasPhotosPermission returns false, the rationale is unreachable (the launcher request hits the merged-manifest check and resolves to denied), and the strip falls back to the CompactTiles layout from the parent PR. The Photos tile (system picker) and Camera tile continue to work — they're permissionless.

Host integration

GutenbergView.resetBlockPickerPhotoPreferences(context) is exposed for host apps that want to clear the rationale-rejection / first-prompt flags from a settings screen.

The demo's ⋮ menu now has a Manage Permissions screen for replaying the rationale flow during review: it shows the current OS state for READ_MEDIA_IMAGES, lets reviewers reset the in-app flags via the library API above, and hands off to the system permission settings for OS-level revokes. revokeSelfPermissionOnKill was the obvious path for the OS-revoke side but requires API 33+; the demo's minSdk = 24, so a Settings hand-off code path is needed regardless. Settings also gives the user an OS-owned confirmation surface and avoids the lifecycle race of an async self-kill. The screen refreshes on ON_RESUME so returning from Settings reflects the new state immediately.

The demo's "Enable Native Inserter" toggle now defaults to on so reviewers see the new strip without flipping a setting.

Test plan

Note: the Photos and Camera tiles open the system picker / camera app, but the picked URI / capture is not yet handed off to the JS editor for block insertion — that round-trip lands in a follow-up PR. The launchers firing and the permission/rationale flow are the parts under test here.

• Open the inserter on first launch. Rationale card shows Allow + Reject alongside the Photos/Camera column.
• Tap Allow → system prompt → grant → strip flips to recent photos, behind the same Photos/Camera column.
• Deny system prompt once → rationale switches to Try Again.
• Deny system prompt twice → rationale switches to Open Settings (system suppresses the prompt).
• Tap Reject in rationale → rationale hides, Photos/Camera reflow into a 88dp full-width row; preference persists across dialog dismiss/relaunch and app cold-start.
• After Reject, grant permission via system Settings → return to the app → strip flips to thumbnails (lifecycle resume picks up the new grant).
• After grant, revoke via system Settings → return to the app → rationale card returns (sticky rejected flag was cleared on grant).
• Tap Photos tile → system photo picker opens (works in all three states).
• Tap Camera tile → camera app opens with a cache-scoped output URI (works in all three states).
• Vertical drag on the photo strip still drags the bottom sheet (LazyRow's nested-scroll dispatch).
• Demo ⋮ → Manage Permissions shows current OS state (Granted / Denied (system will re-prompt) / Denied (system prompt suppressed)).
• Reset flags clears the SharedPreferences; reopening the inserter shows the rationale fresh.
• Open Settings hands off to the system permission detail; toggling there and returning refreshes the state card via the ON_RESUME observer.
• Rationale buttons feel comfortably tappable despite their 32dp visual.
• ./gradlew :Gutenberg:detekt :Gutenberg:assembleDebug :Gutenberg:testDebugUnitTest passes (includes PhotoAccessStateTest).

[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/510")

_{Built from 764b1ab}