fix(order): surface rejection reason, keep sync green, hydrate verdicts

Three issues surfaced once the per-command rejection from the previous
commit actually reached the UI:

1. Sync banner falsely red. `OrderDraftStore.runSync` flipped
   `syncStatus = "error"` whenever any command was rejected and
   advertised a Retry button. A per-command rejection is a
   player-correctable state — the round trip succeeded, the engine
   just refused that command — so the retry can't help. Keep
   `syncStatus = "synced"` on `success`; the red row highlight is
   the visible cue.

2. Rejection reason missing. Add `cmd_error_message: string` to
   `CommandItem` in `pkg/schema/fbs/order.fbs` (appended last to
   preserve existing slot offsets) and regenerate the Go + TS stubs
   for that one type. Plumb the message through `CommandMeta`,
   `Controller.applyCommand`'s `m.Result(code, message)` call, the
   Go transcoder, the UI decoders in `submit.ts` /  `order-load.ts`,
   and the `OrderDraftStore.errorMessages` map. `order-tab.svelte`
   renders it as an italic danger-coloured line under rejected
   commands, with new CSS for `.error-reason`.

3. Verdict lost on navigation. `order-load.ts.decodeCommand` never
   read `cmdApplied`/`cmdErrorCode`, so `hydrateFromServer` fell
   back to a blanket "applied" status — a previously-rejected
   command came back green after a lobby → game round trip. Extend
   the fetch decoder to populate `statuses`/`errorCodes`/
   `errorMessages` maps and have `hydrateFromServer` use them.
   Engine-side persistence already records the verdict on disk —
   verified against the live `0000/order/<id>.json`.

`flatbuffers@25` elides default-int8/int64 fields on write; the Go
transcoder force-slots `cmd_applied=false` / `cmd_error_code=0`
already, the new test fixtures flip `builder.forceDefaults(true)` to
mirror that behaviour so the round trip survives.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pkg/transcoder/order.go

@@ -125,6 +125,7 @@ type encodedCommand struct {
 	cmdID         string
 	cmdApplied    *bool
 	cmdErrCode    *int
+	cmdErrMsg     *string
 	payloadType   fbs.CommandPayload
 	payloadOffset flatbuffers.UOffsetT
 }
@@ -404,6 +405,7 @@ func encodedCommandFromMeta(meta model.CommandMeta, payloadType fbs.CommandPaylo
 		cmdID:         meta.CmdID,
 		cmdApplied:    cloneBoolPointer(meta.CmdApplied),
 		cmdErrCode:    cloneIntPointer(meta.CmdErrCode),
+		cmdErrMsg:     cloneStringPointer(meta.CmdErrMsg),
 		payloadType:   payloadType,
 		payloadOffset: payloadOffset,
 	}
@@ -423,6 +425,11 @@ func decodeOrderCommand(flatCommand *fbs.CommandItem, index int) (model.Decodabl
 		commandMeta.CmdErrCode = &decodedCmdErrCode
 	}
 
+	if cmdErrMsg := flatCommand.CmdErrorMessage(); cmdErrMsg != nil {
+		decodedCmdErrMsg := string(cmdErrMsg)
+		commandMeta.CmdErrMsg = &decodedCmdErrMsg
+	}
+
 	payloadType := flatCommand.PayloadType()
 	if payloadType == fbs.CommandPayloadNONE {
 		return nil, fmt.Errorf("decode order command %d: payload type is NONE", index)
@@ -915,6 +922,15 @@ func cloneIntPointer(value *int) *int {
 	return &cloned
 }
 
+func cloneStringPointer(value *string) *string {
+	if value == nil {
+		return nil
+	}
+
+	cloned := *value
+	return &cloned
+}
+
 // UserGamesCommandToPayload converts model.UserGamesCommand to
 // FlatBuffers bytes suitable for the authenticated gateway transport.
 // `GameID` is required.
@@ -1293,6 +1309,10 @@ func encodeCommandItemVector(builder *flatbuffers.Builder, commands []model.Deco
 			return 0, fmt.Errorf("encode %s: %w", opLabel, err)
 		}
 		cmdID := builder.CreateString(encoded.cmdID)
+		var cmdErrMsg flatbuffers.UOffsetT
+		if encoded.cmdErrMsg != nil {
+			cmdErrMsg = builder.CreateString(*encoded.cmdErrMsg)
+		}
 		fbs.CommandItemStart(builder)
 		fbs.CommandItemAddCmdId(builder, cmdID)
 		if encoded.cmdApplied != nil {
@@ -1303,6 +1323,9 @@ func encodeCommandItemVector(builder *flatbuffers.Builder, commands []model.Deco
 		}
 		fbs.CommandItemAddPayloadType(builder, encoded.payloadType)
 		fbs.CommandItemAddPayload(builder, encoded.payloadOffset)
+		if encoded.cmdErrMsg != nil {
+			fbs.CommandItemAddCmdErrorMessage(builder, cmdErrMsg)
+		}
 		offsets[i] = fbs.CommandItemEnd(builder)
 	}
 	if len(offsets) == 0 {