The level picker explains itself, as it does on iOS

This screen showed chips and no explanation; iOS has carried one all along,
under a comment claiming both apps use the same words. They now do.

The last sentence is the boundary: a level decides who can open a file, not
where it can be put. Neither app stops somebody filing sensitive material
somewhere low, and saying so is the honest half of android#15.

Also repairs a comment the emoji sweep truncated, which left the test
saying 'the -property is NOT enforced'.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

engine/src/test/kotlin/io/flamenet/e2e/LabelTest.kt

@@ -133,8 +133,9 @@ class LabelTest {
     // ---- Writing ---------------------------------------------------------.
 
     /**
-     * Writing is gated by the same range check as reading, and the -property is
-     * NOT enforced, on either platform.
+     * Writing is gated by the same range check as reading, and no-write-down is
+     * NOT enforced, on either platform. Mirrored by ClearanceTests on the Swift
+     * side; the two change together or not at all.
      */
     @Test
     fun `writing uses the same range check as reading, star-property not enforced`() {