Pro: QA backend override, a proof-acquisition floor, and a unit-test class-init fix - #2153

…ation

Reading a SessionProtocol constant runs System.loadLibrary("session_util"), so
doing it from the companion's initialiser made the class impossible to
initialise wherever the native library is absent -- every JVM unit test. Mockito
could not instrument it, and the nine tests constructing a ConversationViewModel
failed with NoClassDefFoundError.

The constants stay single-sourced from libsession; they are just read on first
use rather than on class load.

The debug menu already drives these states through preferences that
ProStatusManager and ProSettingsViewModel read; they were just unreachable from
an automated launch, so the Appium suite could only cover Pro screens on iOS.

sessionProBackendStatus and sessionProLoadingState are named for the state being
simulated rather than for the preference behind them, matching the keys iOS
already accepts, so one cross-platform test has one setup that means the same
thing on both. `useActual` clears an override. Values are mapped explicitly
rather than derived from enum names, so renaming a case cannot silently change
what a test asks for.

Two of the three EXPIRING labels claimed 14 days while the code used 2, which is
how a reader (and a test author) ends up with the wrong value: the label looks
authoritative and is the first thing you see.

EXPIRING_LATER moves 40 -> 30 days so both platforms can assert the same
rendered string. It already sat outside the 7-day window that gates the expiring
CTA and still does, so its behaviour is unchanged -- EXPIRING keeps its 2 days
precisely because it is inside that window and is the only way to trigger the
CTA by hand.

It sat on the ComposeView host in XML while the tap target is the Avatar inside
it. Compose publishes its own semantics tree, so whether the host's description
survived depended on composition timing -- intermittently leaving the avatar
unlabelled for accessibility services, and unfindable by anything addressing it
by description.

Removed from the XML rather than left in both places: the same description on
two nodes of one tree is the ambiguity being fixed, not redundancy. Nothing read
it there -- the id is used as a constraint anchor and for setThemedContent only.

… remaining surfaces

- `SessionProSettingsHeader` applied `clearAndSetSemantics` to the whole column, which
  erases descendants rather than merging them — so the status banner was absent from the
  tree entirely, text and all, and TalkBack announced "Session Pro" over a message users
  never heard. Narrow it to the decorative logo and badge, leaving `extraContent` a sibling
  inside the column that carries `onSizeChanged` (moving it out would change the gradient
  ratio).
- Tag both banner variants with `pro-settings-status-banner`. One id for the slot; the four
  states are told apart by their text.
- Section-header ids for Stats, Manage and Pro Beta Features, via one optional `CategoryCell`
  parameter so the other call sites are untouched.
- Name the conversation-header badge, matching iOS.