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.

backend/internal/adminconsole/views.go

@@ -556,9 +556,15 @@ type FeedbackDetailView struct {
 	CreatedAt         string
 	// Version is the client app build the report was sent from (empty for rows that predate it).
 	Version string
-	// CreatedAtLocal is CreatedAt rendered in the sender's time zone, with TimeZone its label.
-	// Empty when the sender's zone is UTC or unknown — then only the UTC CreatedAt is shown.
-	CreatedAtLocal string
-	TimeZone       string
-	Banned         bool
+	// The Filed time is shown in three zones so the operator can tell what is certainly known from
+	// what is merely defaulted. CreatedAt is the authoritative UTC time. CreatedAtBrowser is that
+	// instant in the client's UTC offset detected at submit (BrowserTZ its "±HH:MM" label), empty
+	// when the client reported none (an older build). CreatedAtUser is that instant in the sender's
+	// saved profile zone (UserTZ its label), empty when the account has no zone beyond the UTC
+	// default — the template then shows "N/A" so the missing datum is explicit.
+	CreatedAtBrowser string
+	BrowserTZ        string
+	CreatedAtUser    string
+	UserTZ           string
+	Banned           bool
 }