feat(server): wire EmbeddingRelevanceScorer into context builder, default level 4

Move embedder construction ahead of the engines so the context pack builder ranks
freeform turns by query relevance (query-conditioned selection). Default
compression_level 4 (format + static cache + token pruning + age-tiering) for a 12b
on a 16k window.

apps/server/src/main/kotlin/com/correx/apps/server/Main.kt

@@ -18,6 +18,7 @@ import com.correx.core.config.ProfileLoader
 import com.correx.core.config.ProviderConfig
 import com.correx.core.context.builder.DefaultContextPackBuilder
 import com.correx.core.context.compression.CompressionPolicy
+import com.correx.core.inference.EmbeddingRelevanceScorer
 import com.correx.infrastructure.compression.HttpTokenPruner
 import com.correx.core.context.compression.DefaultContextCompressor
 import com.correx.core.context.model.TokenBudget
@@ -291,12 +292,16 @@ fun main() {
         WorkspaceTools(registry = wsRegistry, executor = wsExecutor)
     }
 
+    // Constructed before the engines so the context builder can rank freeform turns by relevance
+    // to the current query (pipeline §6, query-conditioned selection). Reused by L3 retrieval below.
+    val embedder = InfrastructureModule.createEmbedderFromConfig(correxConfig.router.embedder)
     val engines = OrchestratorEngines(
         transitionResolver = DefaultTransitionResolver { condition, ctx -> condition.evaluate(ctx) },
         contextPackBuilder = DefaultContextPackBuilder(
             DefaultContextCompressor(),
             policy = CompressionPolicy(correxConfig.orchestration.compressionLevel),
             tokenPruner = HttpTokenPruner(baseUrl = correxConfig.orchestration.tokenPrunerUrl),
+            relevanceScorer = EmbeddingRelevanceScorer(embedder),
         ),
         inferenceRouter = inferenceRouter,
         validationPipeline = ValidationPipeline(
@@ -340,7 +345,6 @@ fun main() {
     val artifactKindRegistry = DefaultArtifactKindRegistry().also { reg ->
         configArtifactKindsEarly.forEach { reg.register(it) }
     }
-    val embedder = InfrastructureModule.createEmbedderFromConfig(correxConfig.router.embedder)
     val l3MemoryStore = InfrastructureModule.createL3MemoryStoreFromConfig(correxConfig.router.l3)
     // Rebuild the L3 metadata map from the ChatTurnEvent log before serving queries:
     // persisted vectors survive restart but the metadata map does not (no-op for