Add console logging for client-side routing decisions

tryClientRoute now logs why it falls through: has-data, no content,
eval failed, or #main-panel not found. tryEvalContent logs the actual
error on catch. Added logWarn platform function (console.warn).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/sx/ref/bootstrap_js.py

@@ -497,6 +497,7 @@ class JSEmitter:
             "store-env-attr": "storeEnvAttr",
             "to-kebab": "toKebab",
             "log-info": "logInfo",
+            "log-warn": "logWarn",
             "log-parse-error": "logParseError",
             "parse-and-load-style-dict": "parseAndLoadStyleDict",
             "_page-routes": "_pageRoutes",
@@ -2625,6 +2626,7 @@ PLATFORM_ORCHESTRATION_JS = """
       }
       return sxRenderWithEnv(source, merged);
     } catch (e) {
+      console.warn("sx:route eval error", e);
       return NIL;
     }
   }
@@ -2974,6 +2976,10 @@ PLATFORM_BOOT_JS = """
     if (typeof console !== "undefined") console.log("[sx-ref] " + msg);
   }
 
+  function logWarn(msg) {
+    if (typeof console !== "undefined") console.warn("[sx-ref] " + msg);
+  }
+
   function logParseError(label, text, err) {
     if (typeof console === "undefined") return;
     var msg = err && err.message ? err.message : String(err);