feat(feedback): capture the app version; show version + local Filed time

Each feedback submission now carries the client app version (__APP_VERSION__),
snapshotted like the interface language: FlatBuffers FeedbackSubmitRequest gains
a version field → gateway transcode → backend, persisted in a new nullable
feedback_messages.app_version column (migration 00003, additive so an image
rollback stays DB-safe). The operator console detail shows the app version and
renders the Filed time in UTC plus the sender's time zone (fmtTimeIn).

Touches: fbs schema + regenerated Go/TS codegen, codec + transport (the client
attaches its build), gateway transcode + backendclient, feedback store/service,
admin view + template, docs (ARCHITECTURE §15, FUNCTIONAL + _ru). Verified:
feedback integration tests (migration + version round-trip), codec round-trip,
check/unit/build green.

docs/ARCHITECTURE.md

@@ -1149,9 +1149,11 @@ Two contours, two secret/variable prefixes (`TEST_` / `PROD_`):
 
 Players reach the operators through a **Feedback** screen (Settings → Info, registered accounts
 only). A message (≤1024 runes) plus an optional single attachment is stored in
-`feedback_messages`; the sender's IP (gateway-forwarded, as for chat) and the submitting
-**channel** (telegram/ios/android/web, client-reported and validated) are recorded. The domain
-is `internal/feedback` (store + service), modelled on the admin chat-moderation surface.
+`feedback_messages`; the sender's IP (gateway-forwarded, as for chat), the submitting
+**channel** (telegram/ios/android/web, client-reported and validated), the **client app version**
+(`__APP_VERSION__`, the build a report was sent from) and a snapshot of the sender's interface
+language are recorded. The domain is `internal/feedback` (store + service), modelled on the admin
+chat-moderation surface.
 
 **Anti-spam.** A player with an unreviewed message (`read_at IS NULL`) cannot submit another; the
 gate is server-side. Because the operator must act before the next message, this is itself the
@@ -1159,8 +1161,10 @@ rate limit — there is no separate per-user feedback limiter.
 
 **Operator review** happens in the server-rendered console (`/_gm/feedback`): an
 unread / read / archived queue with per-user search (the `/users` glob masks), a detail card
-(user content rendered as auto-escaped `html/template` text), and the read / reply / archive /
-delete / delete-all actions — each marks the message read; merely opening the detail does not.
+(user content rendered as auto-escaped `html/template` text; it shows the channel, interface
+language and app version, and the filed time in UTC plus the sender's time zone), and the read /
+reply / archive / delete / delete-all actions — each marks the message read; merely opening the
+detail does not.
 The attachment is served from `/_gm/feedback/:id/attachment` with `X-Content-Type-Options:
 nosniff`: images inline (loaded only via `<img>`, which never executes — a renamed non-image is
 inert), everything else as an `application/octet-stream` download. The UI gates the attachment by