docs(changelog): record T-13/T-9 — archive and trash a mailbox entry, lookup by message number

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

CHANGELOG.md

@@ -7,6 +7,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- **Archive and trash a message in your own mailbox** (`scribe_mailbox_entries.archived_at`
+  and `trashed_at`, migration 009, core-api T-13) — deletion is per mailbox entry, never per
+  message, since a message is retained and shared by every recipient (D-66/D-70). `PATCH
+  /scribe/mailbox/{entry_id}` takes `archived` and `trashed` booleans beside `read` (true sets
+  the timestamp, false clears it); the response carries both states. `GET /scribe/mailbox`
+  takes `view`: `inbox` (default, neither archived nor trashed), `archive` (archived, not
+  trashed), `trash` (trashed, regardless of `archived_at`), `all`. `find` now excludes trashed
+  entries.
+- **Look up a mailbox entry by message number** (core-api T-9) — `GET
+  /scribe/mailbox?message_id=N` answers the caller's own entry for that message, zero or one,
+  in any view, bypassing `unread`/`tag`/`before_id` so no client pages the unread-first/
+  id-descending listing to find one.
+
 ## [1.13.0] - 2026-10-19
 
 ### Added