docs: drop dated self-corrections

Remove dates and "this used to say X" framing from prose and comments.
What the tree does now is the only thing that matters; the history is in
git.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

engine/src/test/kotlin/io/flamenet/e2e/MailboxStateTest.kt

@@ -119,7 +119,7 @@ class MailboxStateTest {
     }
 
     /**
-     * The pin falls back to the pre-2026-08-30 global entry, so a phone already
+     * The pin falls back to the older global entry, so a phone already
      * holding one keeps it rather than starting trust-on-first-use again, and a
      * per-relay entry, once written, wins.
      */