feat: switchable router embedder and L3 backends via config

Adds [router.embedder] and [router.l3] sections to CorrexConfig with
backend selectors. Ships LlamaCppEmbedder that hits llama.cpp's
/embedding endpoint (handles OpenAI-compatible, simple, and array
response shapes; validates dimension). InfrastructureModule gains
createEmbedderFromConfig and createL3MemoryStoreFromConfig that
dispatch on backend value.

Defaults preserve current behavior (noop embedder + in-memory L3).
Switching to "llamacpp" / "turbovec" is a config-only change — no code
edits required. For turbovec backend, the bundled python sidecar
script is extracted from classpath to ~/.cache/correx/ on first use.

infrastructure/src/main/kotlin/com/correx/infrastructure/InfrastructureModule.kt

@@ -6,6 +6,8 @@ import com.correx.core.approvals.DefaultApprovalRepository
 import com.correx.core.artifacts.DefaultArtifactReducer
 import com.correx.core.artifacts.repository.ArtifactRepository
 import com.correx.core.artifactstore.ArtifactStore
+import com.correx.core.config.EmbedderConfig
+import com.correx.core.config.L3Config
 import com.correx.core.events.EventDispatcher
 import com.correx.core.events.stores.EventStore
 import com.correx.core.inference.CapabilityScore
@@ -33,7 +35,10 @@ import com.correx.infrastructure.artifactscas.index.SqliteArtifactIndex
 import com.correx.infrastructure.inference.DefaultProviderRegistry
 import com.correx.infrastructure.inference.commons.ModelDescriptor
 import com.correx.infrastructure.inference.commons.ResidencyMode
+import com.correx.infrastructure.inference.llama.cpp.LlamaCppEmbedder
 import com.correx.infrastructure.inference.llama.cpp.LlamaCppInferenceProvider
+import com.correx.infrastructure.router.turbovec.TurboVecL3MemoryStore
+import com.correx.infrastructure.router.turbovec.TurboVecSidecarConfig
 import com.correx.infrastructure.persistence.SqliteEventStore
 import com.correx.infrastructure.persistence.artifact.LiveArtifactRepository
 import com.correx.infrastructure.tools.DefaultToolRegistry
@@ -49,6 +54,7 @@ import kotlinx.coroutines.runBlocking
 import java.nio.file.Files
 import java.nio.file.Path
 import java.nio.file.Paths
+import java.nio.file.StandardCopyOption
 import java.sql.DriverManager
 
 @Suppress("TooManyFunctions")
@@ -137,6 +143,70 @@ object InfrastructureModule {
 
     fun createInMemoryL3MemoryStore(): L3MemoryStore = InMemoryL3MemoryStore()
 
+    fun createLlamaCppEmbedder(config: EmbedderConfig): Embedder {
+        val url = config.url ?: throw IllegalArgumentException(
+            "EmbedderConfig with backend 'llamacpp' requires non-null 'url'"
+        )
+        return LlamaCppEmbedder(
+            url = url,
+            modelId = config.modelId,
+            dimension = config.dimension,
+        )
+    }
+
+    fun createTurboVecL3MemoryStore(config: L3Config): L3MemoryStore {
+        val scriptPath = config.scriptPath?.let { Paths.get(it) }
+            ?: extractBundledTurboVecScript()
+
+        val persistPath = config.persistPath?.let { Paths.get(it) }
+
+        val sidecarConfig = TurboVecSidecarConfig(
+            pythonExecutable = config.pythonExecutable,
+            scriptPath = scriptPath,
+            dim = config.dim,
+            bitWidth = config.bitWidth,
+            persistPath = persistPath,
+        )
+
+        return TurboVecL3MemoryStore(sidecarConfig)
+    }
+
+    private fun extractBundledTurboVecScript(): Path {
+        val cacheDir = Paths.get(System.getProperty("user.home"), ".cache", "correx")
+        Files.createDirectories(cacheDir)
+
+        val targetPath = cacheDir.resolve("turbovec_sidecar.py")
+
+        val inputStream = InfrastructureModule::class.java.getResourceAsStream("/python/turbovec_sidecar.py")
+            ?: throw IllegalStateException("Could not find bundled turbovec_sidecar.py in classpath")
+
+        inputStream.use { input ->
+            Files.copy(input, targetPath, StandardCopyOption.REPLACE_EXISTING)
+        }
+
+        return targetPath
+    }
+
+    fun createEmbedderFromConfig(config: EmbedderConfig): Embedder {
+        return when (config.backend) {
+            "noop" -> createNoopEmbedder(config.dimension)
+            "llamacpp" -> createLlamaCppEmbedder(config)
+            else -> throw IllegalArgumentException(
+                "Unknown embedder backend: '${config.backend}'. Supported: noop, llamacpp"
+            )
+        }
+    }
+
+    fun createL3MemoryStoreFromConfig(config: L3Config): L3MemoryStore {
+        return when (config.backend) {
+            "in_memory" -> createInMemoryL3MemoryStore()
+            "turbovec" -> createTurboVecL3MemoryStore(config)
+            else -> throw IllegalArgumentException(
+                "Unknown L3 backend: '${config.backend}'. Supported: in_memory, turbovec"
+            )
+        }
+    }
+
     fun createRouterFacade(
         eventStore: EventStore,
         inferenceRouter: InferenceRouter,