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.

ui/src/gen/fbs/scrabblefb/feedback-submit-request.ts

@@ -63,8 +63,15 @@ version(optionalEncoding?:any):string|Uint8Array|null {
   return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
 }
 
+browserTz():string|null
+browserTz(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
+browserTz(optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 14);
+  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
+}
+
 static startFeedbackSubmitRequest(builder:flatbuffers.Builder) {
-  builder.startObject(5);
+  builder.startObject(6);
 }
 
 static addBody(builder:flatbuffers.Builder, bodyOffset:flatbuffers.Offset) {
@@ -99,18 +106,23 @@ static addVersion(builder:flatbuffers.Builder, versionOffset:flatbuffers.Offset)
   builder.addFieldOffset(4, versionOffset, 0);
 }
 
+static addBrowserTz(builder:flatbuffers.Builder, browserTzOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(5, browserTzOffset, 0);
+}
+
 static endFeedbackSubmitRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createFeedbackSubmitRequest(builder:flatbuffers.Builder, bodyOffset:flatbuffers.Offset, attachmentOffset:flatbuffers.Offset, attachmentNameOffset:flatbuffers.Offset, channelOffset:flatbuffers.Offset, versionOffset:flatbuffers.Offset):flatbuffers.Offset {
+static createFeedbackSubmitRequest(builder:flatbuffers.Builder, bodyOffset:flatbuffers.Offset, attachmentOffset:flatbuffers.Offset, attachmentNameOffset:flatbuffers.Offset, channelOffset:flatbuffers.Offset, versionOffset:flatbuffers.Offset, browserTzOffset:flatbuffers.Offset):flatbuffers.Offset {
   FeedbackSubmitRequest.startFeedbackSubmitRequest(builder);
   FeedbackSubmitRequest.addBody(builder, bodyOffset);
   FeedbackSubmitRequest.addAttachment(builder, attachmentOffset);
   FeedbackSubmitRequest.addAttachmentName(builder, attachmentNameOffset);
   FeedbackSubmitRequest.addChannel(builder, channelOffset);
   FeedbackSubmitRequest.addVersion(builder, versionOffset);
+  FeedbackSubmitRequest.addBrowserTz(builder, browserTzOffset);
   return FeedbackSubmitRequest.endFeedbackSubmitRequest(builder);
 }
 }

ui/src/lib/codec.test.ts

@@ -76,20 +76,22 @@ describe('codec', () => {
   it('round-trips a feedback submit and decodes state + unread', () => {
     const att = new Uint8Array([1, 2, 3, 4]);
     const req = fb.FeedbackSubmitRequest.getRootAsFeedbackSubmitRequest(
-      new ByteBuffer(encodeFeedbackSubmit('please fix', att, 'shot.png', 'ios', 'v1.2.3')),
+      new ByteBuffer(encodeFeedbackSubmit('please fix', att, 'shot.png', 'ios', 'v1.2.3', '+03:00')),
     );
     expect(req.body()).toBe('please fix');
     expect(req.attachmentName()).toBe('shot.png');
     expect(req.channel()).toBe('ios');
     expect(req.version()).toBe('v1.2.3');
+    expect(req.browserTz()).toBe('+03:00');
     expect(Array.from(req.attachmentArray() ?? [])).toEqual([1, 2, 3, 4]);
 
     // No attachment: the vector is empty.
     const req2 = fb.FeedbackSubmitRequest.getRootAsFeedbackSubmitRequest(
-      new ByteBuffer(encodeFeedbackSubmit('hi', null, '', 'web', 'dev')),
+      new ByteBuffer(encodeFeedbackSubmit('hi', null, '', 'web', 'dev', '+00:00')),
     );
     expect(req2.body()).toBe('hi');
     expect(req2.version()).toBe('dev');
+    expect(req2.browserTz()).toBe('+00:00');
     expect(req2.attachmentLength()).toBe(0);
 
     // State carrying a reply.

ui/src/lib/codec.ts

@@ -490,6 +490,7 @@ export function encodeFeedbackSubmit(
   attachmentName: string,
   channel: string,
   version: string,
+  browserTz: string,
 ): Uint8Array {
   const b = new Builder(256);
   const bodyOff = b.createString(body);
@@ -497,12 +498,14 @@ export function encodeFeedbackSubmit(
   const nameOff = b.createString(attachmentName);
   const chOff = b.createString(channel);
   const verOff = b.createString(version);
+  const tzOff = b.createString(browserTz);
   fb.FeedbackSubmitRequest.startFeedbackSubmitRequest(b);
   fb.FeedbackSubmitRequest.addBody(b, bodyOff);
   if (attOff) fb.FeedbackSubmitRequest.addAttachment(b, attOff);
   fb.FeedbackSubmitRequest.addAttachmentName(b, nameOff);
   fb.FeedbackSubmitRequest.addChannel(b, chOff);
   fb.FeedbackSubmitRequest.addVersion(b, verOff);
+  fb.FeedbackSubmitRequest.addBrowserTz(b, tzOff);
   return finish(b, fb.FeedbackSubmitRequest.endFeedbackSubmitRequest(b));
 }
 

ui/src/lib/transport.ts

@@ -10,6 +10,7 @@ import { createConnectTransport } from '@connectrpc/connect-web';
 import { Gateway } from '../gen/edge/v1/edge_pb';
 import { GatewayError, type GatewayClient } from './client';
 import * as codec from './codec';
+import { browserOffset } from './profileValidation';
 import { registerProbe, reportOffline, reportOnline } from './connection.svelte';
 import { backoffMs, isConnectionCode, retryable, toGatewayError } from './retry';
 
@@ -147,9 +148,10 @@ export function createTransport(baseUrl: string): GatewayClient {
       await exec('chat.read', codec.encodeGameAction(id));
     },
     async feedbackSubmit(body, attachment, attachmentName, channel) {
-      // The app build (Vite define) rides with the report so the operator sees which version
-      // it came from; the caller need not pass it.
-      await exec('feedback.submit', codec.encodeFeedbackSubmit(body, attachment, attachmentName, channel, __APP_VERSION__));
+      // The app build (Vite define) and the device's detected UTC offset ride with the report
+      // so the operator sees which version it came from and the local time it was filed; the
+      // caller need not pass them.
+      await exec('feedback.submit', codec.encodeFeedbackSubmit(body, attachment, attachmentName, channel, __APP_VERSION__, browserOffset()));
     },
     async feedbackGet() {
       return codec.decodeFeedbackState(await exec('feedback.get', codec.empty()));