fix: account store ANR and crash hardening for 1.0.11

[findleyl]

Fixes the input-dispatch ANR reported in AccountStore.get_all on 1.0.11, and hardens the Compose paths most likely behind the IllegalStateException crashes.

• AccountStore reads no longer wait on the write lock. Writes are coalesced on a background thread, and unchanged updates are skipped. Switching accounts saves the previous tokens off the main thread.
• UnifiedPush callbacks run on a background thread instead of the main thread.
• Window-position reads in glass chrome, acrylic, context chips, shimmer, and mail detail are guarded when the node is detached.
• Compose content capture is turned off at startup.
• Effect-driven focus requests on sign-in, search, and settings search are guarded.

Unit tests: 4,333 passed, including the new AccountStoreTest. compileFullReleaseKotlin succeeds.