Android overhaul: stale comments and the module README

* Milestone and ownership notes that no longer hold ("owned by M5/M6/M8", "M8 replaces it", "(M8b)", "M7x add",
  "proposed decision in the M5 report", which is D-027 and D-028) in build scripts, :core:design, :core:fakes, :data,
  :app, :core:model and the settings string files.
* SyncEngine: the clock_skew KDoc sat orphaned above restampAfterClockSkew's; it now documents renewMutationId.
* libs.versions.toml header: no milestone, the drift date.
* README: the module table as built (no owners, no DebugFakesModule, which M8 removed), the test fixtures in the
  architecture check and the shared screenshot harness.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

android/gradle/libs.versions.toml

@@ -1,5 +1,5 @@
-# Kvitt version catalog. Versions are the latest stable releases on Google Maven / Maven Central as of 2026-10-17
-# (milestone M2b). Drift: python3 tools/dependency-report/latest.py
+# Kvitt version catalog: the latest stable releases on Google Maven / Maven Central (no drift on 2026-10-18).
+# Drift: python3 tools/dependency-report/latest.py
 [versions]
 minSdk = "36"
 compileSdk = "37"
@@ -27,8 +27,8 @@ coil = "3.6.3"
 junit = "4.13.2"
 robolectric = "4.17"
 roborazzi = "1.76.0"
-# M8 (2026-10-18): Firebase BoM 35.0.2 (firebase-messaging 26.0.0) and the Google services plugin 4.5.0, the latest
-# stable per firebase.google.com/support/release-notes/android
+# Firebase BoM 35.0.2 (firebase-messaging 26.0.0) and the Google services plugin 4.5.0, the latest stable per
+# firebase.google.com/support/release-notes/android on 2026-10-18
 firebaseBom = "35.0.2"
 googleServices = "4.5.0"