feat(tui): event-derived ordering + retire Kotlin TUI

Rebuild the Go TUI transcript from the event stream instead of
optimistic local echoes. ChatTurnEvent now maps to ServerMessage.ChatTurn
(chat.turn); the TUI auto-vivifies sessions and renders user+router turns
from events. SessionStarted is de-special-cased into SessionAnnounced
(still carries workflowId), dropping the router.response shadow and
optimistic echoes.

Delete the unused Kotlin TUI (apps/tui) and add a kotlinx<->Go
golden-fixture test to lock the wire protocol. Gitignore server runtime
logs.

apps/tui-go/internal/protocol/protocol.go

@@ -1,7 +1,7 @@
 // Package protocol implements the correx WebSocket wire contract used to talk
 // to apps/server over /stream. The server (Kotlin/kotlinx.serialization) uses a
 // "type" class discriminator. Server->client variants carry @SerialName values
-// (e.g. "session.started"); client->server variants have no @SerialName, so the
+// (e.g. "session.announced"); client->server variants have no @SerialName, so the
 // discriminator is the fully-qualified Kotlin class name.
 package protocol
 
@@ -13,7 +13,8 @@ const clientPrefix = "com.correx.apps.server.protocol.ClientMessage."
 
 // Server message discriminator values (@SerialName on ServerMessage variants).
 const (
-	TypeSessionStarted   = "session.started"
+	TypeSessionAnnounced = "session.announced"
+	TypeChatTurn         = "chat.turn"
 	TypeSessionPaused    = "session.paused"
 	TypeSessionResumed   = "session.resumed"
 	TypeSessionCompleted = "session.completed"
@@ -54,6 +55,8 @@ type ServerMessage struct {
 	WorkflowID  string  `json:"workflowId"`
 	StageID     string  `json:"stageId"`
 	ToolName    string  `json:"toolName"`
+	Role        string  `json:"role"`
+	TurnID      string  `json:"turnId"`
 	Reason      string  `json:"reason"`
 	Summary     string  `json:"outputSummary"`
 	Response    string  `json:"responseText"`
@@ -168,7 +171,7 @@ func Decode(raw []byte) (ServerMessage, error) {
 // and are applied immediately.
 func (m ServerMessage) IsEventBearing() bool {
 	switch m.Type {
-	case TypeSessionStarted, TypeSessionPaused, TypeSessionResumed,
+	case TypeSessionAnnounced, TypeChatTurn, TypeSessionPaused, TypeSessionResumed,
 		TypeSessionCompleted, TypeSessionFailed,
 		TypeStageStarted, TypeStageCompleted, TypeStageFailed,
 		TypeInferenceStarted, TypeInferenceDone, TypeInferenceTimeout,