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_test.go

@@ -94,6 +94,7 @@ func TestUserGamesOrderResponsePayloadRoundTrip(t *testing.T) {
 	applied := true
 	rejected := false
 	errCode := 7
+	errMsg := "rename failed: planet does not exist"
 	source := &model.UserGamesOrder{
 		GameID:    uuid.MustParse("aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee"),
 		UpdatedAt: 99,
@@ -104,7 +105,7 @@ func TestUserGamesOrderResponsePayloadRoundTrip(t *testing.T) {
 				Name:        "alpha",
 			},
 			&model.CommandPlanetRename{
-				CommandMeta: commandMeta("cmd-2", model.CommandTypePlanetRename, &rejected, &errCode),
+				CommandMeta: commandMetaWithMsg("cmd-2", model.CommandTypePlanetRename, &rejected, &errCode, &errMsg),
 				Number:      6,
 				Name:        "beta",
 			},
@@ -254,10 +255,15 @@ func TestInt64ToInt(t *testing.T) {
 }
 
 func commandMeta(id string, cmdType model.CommandType, applied *bool, errCode *int) model.CommandMeta {
+	return commandMetaWithMsg(id, cmdType, applied, errCode, nil)
+}
+
+func commandMetaWithMsg(id string, cmdType model.CommandType, applied *bool, errCode *int, errMsg *string) model.CommandMeta {
 	return model.CommandMeta{
 		CmdType:    cmdType,
 		CmdID:      id,
 		CmdApplied: applied,
 		CmdErrCode: errCode,
+		CmdErrMsg:  errMsg,
 	}
 }