feat(config): expose router generation + narration knobs in config file

The router/narration model behaviour was hardcoded (Main built RouterConfig()
with defaults). Surface it under the [router] section so it's tunable without a
rebuild:

  [router]            conversation_keep_last, retrieval_k, token_budget
  [router.generation] temperature, top_p, max_tokens          (chat/steering)
  [router.narration]  temperature, top_p, max_tokens, max_per_run

ConfigLoader parses the new sections (adds asDouble); Main maps the config-layer
RouterConfig onto the domain RouterConfig and threads narration.max_per_run into
ServerModule. All values default to the previous constants, so behaviour is
unchanged when the sections are absent. Documents the block in sample-config.toml
and adds parser tests for present/absent cases.

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

@@ -14,10 +14,12 @@ import com.correx.core.config.CorrexConfig
 import com.correx.core.config.ProviderConfig
 import com.correx.core.context.builder.DefaultContextPackBuilder
 import com.correx.core.context.compression.DefaultContextCompressor
+import com.correx.core.context.model.TokenBudget
 import com.correx.core.events.EventDispatcher
 import com.correx.core.events.stores.EventStore
 import com.correx.core.inference.CapabilityScore
 import com.correx.core.inference.DefaultInferenceRouter
+import com.correx.core.inference.GenerationConfig
 import com.correx.core.inference.InferenceProjector
 import com.correx.core.inference.InferenceRepository
 import com.correx.core.inference.InferenceRouter
@@ -246,10 +248,26 @@ fun main() {
     // persisted vectors survive restart but the metadata map does not (no-op for
     // non-rehydratable backends like in_memory).
     runBlocking { L3MetadataRehydrator(eventStore).rehydrate(l3MemoryStore) }
+    // Map the config-file [router] block onto the domain RouterConfig the facade uses.
+    val domainRouterConfig = RouterConfig(
+        conversationKeepLast = routerConfig.conversationKeepLast,
+        retrievalK = routerConfig.retrievalK,
+        tokenBudget = TokenBudget(limit = routerConfig.tokenBudget),
+        generationConfig = GenerationConfig(
+            temperature = routerConfig.generation.temperature,
+            topP = routerConfig.generation.topP,
+            maxTokens = routerConfig.generation.maxTokens,
+        ),
+        narrationGenerationConfig = GenerationConfig(
+            temperature = routerConfig.narration.temperature,
+            topP = routerConfig.narration.topP,
+            maxTokens = routerConfig.narration.maxTokens,
+        ),
+    )
     val routerFacade = InfrastructureModule.createRouterFacade(
         eventStore = eventStore,
         inferenceRouter = inferenceRouter,
-        config = RouterConfig(),
+        config = domainRouterConfig,
         tokenizer = firstProvider.tokenizer,
         embedder = embedder,
         l3MemoryStore = l3MemoryStore,
@@ -289,6 +307,7 @@ fun main() {
         modelSwapper = modelSwapper,
         resourceProbe = resourceProbe,
         workspaceResolver = workspaceResolver,
+        narrationMaxPerRun = routerConfig.narration.maxPerRun,
     )
     module.start()
     log.info("==============================")