Stage 17 round 6 (#18, PR D): admin Messages moderation section

A new /_gm/messages console page lists posted chat messages (nudges
excluded) newest-first — time, source (guest/robot/oldest identity kind),
sender (linked to the user card), IP, body, game (linked to the game card)
— searchable by sender name / external-id glob masks and pinnable to one
game (?game=) or sender (?user=), linked from the game and user cards.

The list query lives in social (raw SQL, kind='message', source via a SQL
CASE), reusing the now-exported account.LikePattern. Server-rendered
adminconsole MessagesView + messages.gohtml, 50/page via the shared pager.

Tests: adminconsole render case; backend integration AdminListMessages
(real Postgres) — nudge exclusion, game/sender pins, glob masks, source.
Docs: ARCHITECTURE section 8 chat moderation, PLAN round-6.

docs/ARCHITECTURE.md

@@ -375,7 +375,11 @@ English game the Latin pool.
   lightly obfuscated forms) are rejected, since the chat is for quick reactions,
   not contact exchange. Each message stores the sender's IP (forwarded by the
   gateway in Stage 6) for moderation. A sender who has disabled chat cannot post,
-  and messages from a blocked sender are hidden from the viewer.
+  and messages from a blocked sender are hidden from the viewer. The operator console
+  has a **Messages** section (Stage 17) that lists posted messages (nudges excluded)
+  newest-first with the sender's resolved name, **source** (guest / robot / oldest
+  identity kind), IP and game, searchable by sender name / external-id glob masks and
+  pinnable to one game or sender (linked from the game and user cards).
 - **Nudge**: folded into the chat as a `nudge` message kind. The player awaiting
   the opponent may nudge **once per hour per game**; it is not allowed on one's own
   turn. The platform-native delivery is wired with the gateway / platform