refactor(upgrade): Converge GPlay billing on the canonical stack

Replaces capod's older billing core, upgrade UI and their tests with the
canonical sdmaid-se stack at the pinned revision.

Core (gplay): BillingManager/BillingConnection/BillingConnectionProvider on
billing 8.3 with the centralized connect loop, merging purchases-listener
overlay and the canonical ack pipeline; the dying ack collector, the
ackedTokens gate and the in-billing foreground loop are gone. Full canonical
exception set (internal/network/offer-unavailable added), OurSku with capod's
product ids, BillingCache with snapshot()/episode-guarded stampLastProState.

FOSS: UpgradeControlFoss becomes UpgradeRepoFoss and exposes the canonical API
surface over capod's RETAINED FossUpgrade/FossCache schema — existing supporter
records must keep decoding.

Diagnostics: UpgradeDiagnostics + gplay/foss implementations, read by
RecorderModule next to CurriculumVitae's Pro history as two independent,
isolated header reads.

UI: canonical upgrade screens for both flavors under common/upgrade/ui with
capod chrome (M3 AlertDialog keeping rotation-safety, capod Scaffold, capod
previews). Nav.Main.Upgrade gains `forced`. Entitlement refresh moves to a
per-resume, unthrottled MainActivity call.

Strings reuse capod's existing translated ids wherever equivalent; only
referenced-but-missing ones are authored.

mockk 1.12.4 -> 1.14.9: 1.12.4 cannot synthesize a sealed-class return value
while recording, which the ported restore tests need.

app/src/main/res/values/strings.xml

@@ -610,4 +610,6 @@
     <string name="press_controls_reset_confirm_message">Reset all press mappings to defaults?</string>
     <string name="device_settings_noise_control_open_press_controls_action">Open Press Controls</string>
 
+    <string name="general_navigate_up_action">Navigate up</string>
+    <string name="general_progress_loading">Loading</string>
 </resources>