feat(android): add Photos and Camera tiles to block inserter

[jkmassel]

Summary

Adds a Photos / Camera quick-launch row between the inserter's header and category tabs. First slice of a four-part split of #479; covers just the permissionless tiles.

• Photos tile uses ActivityResultContracts.PickVisualMedia — the system photo picker, no manifest permission required.
• Camera tile uses ACTION_IMAGE_CAPTURE against a cache-scoped FileProvider URI. The library does not declare or request CAMERA — but per the MediaStore.ACTION_IMAGE_CAPTURE docs, if a host app does declare CAMERA in its merged manifest, Android requires the host to hold it at runtime before the intent dispatches. That's a host-app concern, not a library one — flagging it here so the follow-up that wires up the hand-off doesn't get surprised.

The library declares its own FileProvider keyed off ${applicationId}.gutenberg.fileprovider so it can't collide with one a host app already declares.

No uses-permission lines are added in this PR. The recent-photos thumbnail strip that needs READ_MEDIA_IMAGES lands in the follow-up.

Light mode	Dark mode

Design notes

• The icon and label inside each tile are deliberately tight — no Spacer between them. The block tiles below use an 8dp gap; the media tiles are intentionally punchier to read as quick actions, not as members of the block grid.

What does not land here (follow-ups)

• Recent-photos thumbnail strip, photo-permission rationale, and the READ_MEDIA_IMAGES / READ_EXTERNAL_STORAGE declarations — next PR in the stack.
• Android 14 READ_MEDIA_VISUAL_USER_SELECTED partial-access support and the "Manage" tile — PR after that.
• Touch-target accessibility fix for the existing category chips — independent PR.

Result-callback inertness

Both launcher result callbacks are intentionally empty:

ActivityResultContracts.PickVisualMedia()
) { /* picked uri — hand-off to editor insertion is a follow-up */ }

The picked URI / camera capture needs to round-trip through WebViewAssetLoader so the JS editor can fetch() it — that hand-off is a follow-up. Until then, this whole sheet is gated behind the demo's "Enable Native Inserter" toggle, so users outside that opt-in don't see the no-op buttons.

A TODO on createCameraOutputUri flags that each Camera tap creates an orphan file in the cache today; cleanup lands when the hand-off does.

Test plan

• Open the inserter in the demo app. Photos and Camera tiles render above the category tabs.
• Tap Photos → system photo picker opens. Pick or cancel → sheet returns to the inserter intact.
• Tap Camera → camera app opens with a cache-scoped output URI. Capture or cancel → sheet returns to the inserter intact.
• Camera tile is hidden on devices that don't report FEATURE_CAMERA_ANY (tablet/emulator without a camera).
• ./gradlew :Gutenberg:detekt :Gutenberg:assembleDebug :Gutenberg:testDebugUnitTest passes.

[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/509")

_{Built from 7e94992}

[adalpari]

Just made a small change related to recomposition.
But overall, the PR looks good to me! 🚢 it!!