fix(desktop): refresh overlapping profile batches

[PrimePattern]

Summary

• keep long-lived aggregate users-batch queries synchronized when another batch key refreshes the same profile
• propagate both display-name and avatar updates to the Direct Messages sidebar without requiring an app restart
• remove stale profile entries when a fresh batch reports them missing

Root cause

The sidebar's aggregate profile query could retain an older empty/missing result while a different users-batch query successfully refreshed the same people. The fresh result populated the relay-scoped label cache and per-pubkey cache, but did not update already-mounted aggregate observers, so DM rows stayed on pubkey fallbacks until remount/refetch.

Verification

• pnpm check
• pnpm test — 4,389 passed, 0 failed
• pnpm build
• regression tests cover overlapping-query profile/avatar refresh and fresh missing-profile eviction

Originated from Buzz channel 1aa20aee-df60-40f4-81c4-16a6bda270ce, thread efa9990b62a934907adfdd0c100c026b06c8c677afe6608458c7b88c0f14653a.