feat(feedback): capture the browser UTC offset; Filed time in three zones

The account time zone defaults to UTC until a player saves a profile, so a
report's Filed time could only render in UTC even for a player clearly in
another zone. Capture the client's detected "±HH:MM" offset (browser_tz) with
each submission and show the Filed time in three zones in the operator console
— UTC, the browser offset detected at submit, and the sender's saved profile
zone — each shown "N/A" when not known, so the operator can tell what is
certainly known from what is merely defaulted.

- Thread browser_tz through the fbs envelope (+ Go/TS codegen), the gateway
  transcode + backend client, and the backend feedback service/store; add the
  column via migration 00004 (additive, image-rollback-safe).
- Fix fmtTimeIn to resolve "±HH:MM" offsets via account.ResolveZone;
  time.LoadLocation alone silently fell back to UTC for offset zones, which is
  the second reason a "+02:00" sender showed only UTC.
- Update ARCHITECTURE/FUNCTIONAL(+ru) docs and the feedback integration test.

docs/ARCHITECTURE.md

@@ -1151,8 +1151,8 @@ Players reach the operators through a **Feedback** screen (Settings → Info, re
 only). A message (≤1024 runes) plus an optional single attachment is stored in
 `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
+(`__APP_VERSION__`, the build a report was sent from), the client's **detected UTC offset** at
+submit (`browser_tz`, `±HH:MM`) 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
@@ -1162,7 +1162,8 @@ 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; it shows the channel, interface
-language and app version, and the filed time in UTC plus the sender's time zone), and the read /
+language and app version, and the filed time in three zones — UTC, the browser offset detected at
+submit, and the sender's saved profile zone, each `N/A` when not known), 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: