fix: complete P4 audit findings — steering wiring, generation config

P4-1: Wire steering to actually work (advisory-only):
  - RouterFacade emits SteeringNoteAddedEvent via event store in STEERING mode
  - SessionOrchestrator reads steering notes from event store and includes them
    as ContextEntry objects (sourceType=steeringNote) in stage context packs
  - Delete dead SteeringNote data class; single vocabulary = SteeringNoteAddedEvent
  - Add optional validateSteering callback to DefaultRouterFacade for future
    ValidationPipeline wiring (avoids cross-core dependency)
  - Update RouterFacadeTest to assert event emission

P4-2: Router FACE — move hardcoded generation config:
  - Add GenerationConfig field to RouterConfig with same defaults
  - RouterFacade uses config.generationConfig instead of inline literals
  - (Remaining P4-2 items: conversation persistence and coordination
    semantics are design decisions requiring ADRs, deferred)

core/router/src/main/kotlin/com/correx/core/router/RouterFacade.kt

@@ -1,10 +1,15 @@
 package com.correx.core.router
 
+import com.correx.core.events.events.EventMetadata
+import com.correx.core.events.events.NewEvent
+import com.correx.core.events.events.SteeringNoteAddedEvent
 import com.correx.core.events.stores.EventStore
+import com.correx.core.events.types.CausationId
+import com.correx.core.events.types.CorrelationId
+import com.correx.core.events.types.EventId
 import com.correx.core.events.types.InferenceRequestId
 import com.correx.core.events.types.SessionId
 import com.correx.core.events.types.StageId
-import com.correx.core.inference.GenerationConfig
 import com.correx.core.inference.InferenceRequest
 import com.correx.core.inference.InferenceRouter
 import com.correx.core.inference.ModelCapability
@@ -31,6 +36,7 @@ class DefaultRouterFacade(
     private val inferenceRouter: InferenceRouter,
     private val eventStore: EventStore,
     private val config: RouterConfig,
+    private val validateSteering: (suspend (String) -> String?)? = null,
 ) : RouterFacade {
 
     private val histories = ConcurrentHashMap<SessionId, MutableList<RouterTurn>>()
@@ -55,11 +61,7 @@ class DefaultRouterFacade(
             sessionId = sessionId,
             stageId = effectiveStageId,
             contextPack = contextPack,
-            generationConfig = GenerationConfig(
-                temperature = 0.7,
-                topP = 0.9,
-                maxTokens = 512,
-            ),
+            generationConfig = config.generationConfig,
             responseFormat = ResponseFormat.Text,
         )
         val inferenceResponse = provider.infer(inferenceRequest)
@@ -67,11 +69,28 @@ class DefaultRouterFacade(
 
         history.add(RouterTurn(role = TurnRole.ROUTER, content = content, timestamp = Clock.System.now()))
 
-        // NOTE: SteeringNoteAddedEvent emission is deferred to P4-1, which will wire
-        // proper validation (via ValidationPipeline) and consumption by the context builder.
-        // The current SteeringNoteAddedEvent had wrong content (user raw input instead of
-        // LLM-processed steering text) and was emitted without validation (P0-6).
-        // The steeringEmitted flag below still informs the TUI that steering mode was used.
+        if (mode == ChatMode.STEERING) {
+            val validationError = validateSteering?.invoke(content)
+            if (validationError == null) {
+                eventStore.append(
+                    NewEvent(
+                        metadata = EventMetadata(
+                            eventId = EventId(UUID.randomUUID().toString()),
+                            sessionId = sessionId,
+                            timestamp = Clock.System.now(),
+                            schemaVersion = 1,
+                            causationId = null,
+                            correlationId = null,
+                        ),
+                        payload = SteeringNoteAddedEvent(
+                            sessionId = sessionId,
+                            content = content,
+                            stageId = effectiveStageId.takeIf { it != StageId.NONE },
+                        ),
+                    ),
+                )
+            }
+        }
 
         return RouterResponse(content = content, steeringEmitted = (mode == ChatMode.STEERING))
     }
@@ -80,4 +99,4 @@ class DefaultRouterFacade(
 enum class ChatMode {
     CHAT,
     STEERING,
-}
+}

core/router/src/main/kotlin/com/correx/core/router/model/RouterConfig.kt

@@ -1,10 +1,16 @@
 package com.correx.core.router.model
 
 import com.correx.core.context.model.TokenBudget
+import com.correx.core.inference.GenerationConfig
 import kotlinx.serialization.Serializable
 
 @Serializable
 data class RouterConfig(
     val conversationKeepLast: Int = 6,
     val tokenBudget: TokenBudget = TokenBudget(limit = 4096),
+    val generationConfig: GenerationConfig = GenerationConfig(
+        temperature = 0.7,
+        topP = 0.9,
+        maxTokens = 512,
+    ),
 )