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.

core/config/src/main/kotlin/com/correx/core/config/ConfigLoader.kt

@@ -624,7 +624,7 @@ object ConfigLoader {
                 asInt(orchestrationSection["journal_compaction_token_threshold"], 2_000),
             resumeAbandonedMaxAgeMinutes =
                 asLong(orchestrationSection["resume_abandoned_max_age_minutes"], 1_440),
-            compressionLevel = asInt(orchestrationSection["compression_level"], 2),
+            compressionLevel = asInt(orchestrationSection["compression_level"], 4),
             tokenPrunerUrl =
                 asString(orchestrationSection["token_pruner_url"], "http://127.0.0.1:8199"),
         )

core/config/src/main/kotlin/com/correx/core/config/CorrexConfig.kt

@@ -64,9 +64,10 @@ data class OrchestrationKnobs(
     /**
      * Context compression pipeline level (docs/plans/correx-compression-pipeline.md §5), additive
      * 1..9. Default 2 = free format-compress + static cache. Raise toward the 16k wall; ≥3 needs
-     * the LLMLingua-2 sidecar at [tokenPrunerUrl] (fails open if absent).
+     * the LLMLingua-2 sidecar at [tokenPrunerUrl] (fails open if absent). Default 4 = format +
+     * static cache + token pruning + age-tiering, sized for a 12b on a 16k window.
      */
-    val compressionLevel: Int = 2,
+    val compressionLevel: Int = 4,
     val tokenPrunerUrl: String = "http://127.0.0.1:8199",
 )