fix(game): #59 — per-command rejection on PUT /api/v1/order

Validation of a player's order now applies every command against a
transient game-state snapshot and records the per-command outcome
(cmdApplied, cmdErrorCode) in each command's meta. The order is
persisted even when some commands are rejected, and the response is
202 + UserGamesOrder so clients can surface the partial failure
without the chain collapsing into "downstream service is unavailable".

Pkg/error consts are reshelved onto three explicit ranges with a
package doc and helpers (IsInternalCode/IsInputCode/IsGameStateCode):
1xxx internal/server (500/501), 2xxx structural input (400), 3xxx
game-state per-command rejection (400 when escaping HTTP, otherwise
recorded as cmdErrorCode). Two pre-existing typos fixed mechanically
(ErrBeakGroupNumberNotEnough -> ErrBreakGroupNumberNotEnough,
ErrRaceExinct -> ErrRaceExtinct) along with all callsites.

Engine errorResponse maps *GenericError by shelf rather than mapping
everything to 500. The Quit-not-last structural check in
Controller.ValidateOrder is preserved and its type assertion fixed
(was a value assertion against a pointer-typed command, so the check
silently never fired).

Backend, gateway and UI are unchanged — they were already correct on
the 202 path; only the engine collapsing per-command rejection into
500 was needed.

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

game/internal/controller/race_test.go

@@ -28,10 +28,10 @@ func TestRaceVote(t *testing.T) {
 		e.GenericErrorText(e.ErrInputUnknownRace))
 	assert.ErrorContains(t,
 		g.RaceVote(Race_0.Name, Race_Extinct.Name),
-		e.GenericErrorText(e.ErrRaceExinct))
+		e.GenericErrorText(e.ErrRaceExtinct))
 	assert.ErrorContains(t,
 		g.RaceVote(Race_Extinct.Name, Race_1.Name),
-		e.GenericErrorText(e.ErrRaceExinct))
+		e.GenericErrorText(e.ErrRaceExtinct))
 }
 
 func TestRaceRelation(t *testing.T) {
@@ -54,10 +54,10 @@ func TestRaceRelation(t *testing.T) {
 		e.GenericErrorText(e.ErrInputUnknownRace))
 	assert.ErrorContains(t,
 		g.RaceRelation(Race_0.Name, Race_Extinct.Name, "War"),
-		e.GenericErrorText(e.ErrRaceExinct))
+		e.GenericErrorText(e.ErrRaceExtinct))
 	assert.ErrorContains(t,
 		g.RaceRelation(Race_Extinct.Name, Race_0.Name, "War"),
-		e.GenericErrorText(e.ErrRaceExinct))
+		e.GenericErrorText(e.ErrRaceExtinct))
 }
 
 func TestRaceQuit(t *testing.T) {
@@ -69,7 +69,7 @@ func TestRaceQuit(t *testing.T) {
 
 	assert.ErrorContains(t,
 		g.RaceQuit(Race_Extinct.Name),
-		e.GenericErrorText(e.ErrRaceExinct))
+		e.GenericErrorText(e.ErrRaceExtinct))
 
 	assert.NoError(t, g.RaceQuit(Race_0.Name))
 	assert.Equal(t, 3, int(c.Race(Race_0_idx).TTL))
@@ -84,7 +84,7 @@ func TestRaceID(t *testing.T) {
 	assert.ErrorContains(t, err, e.GenericErrorText(e.ErrInputUnknownRace))
 
 	_, err = g.RaceID(Race_Extinct.Name)
-	assert.ErrorContains(t, err, e.GenericErrorText(e.ErrRaceExinct))
+	assert.ErrorContains(t, err, e.GenericErrorText(e.ErrRaceExtinct))
 
 	id, err := g.RaceID(Race_0.Name)
 	assert.NoError(t, err)