Expand test coverage across server, agent, and web; fix bugs found during audit.

Adds hundreds of unit/integration/e2e tests, fixes WS bcrypt auth, config merge, fleet analytics, agent schedule/log tail, and documents stale PROBLEMS items. Updates PROBLEMS.md, README, and test scripts; ignores local spread-kits and coverage dirs.

server/web/src/pages/BuilderPage.tsx

@@ -635,6 +635,20 @@ export default function BuilderPage() {
     fusionPrepFile,
   ]);
 
+  // Cancel any in-progress server-side build when the component unmounts
+  // (e.g. user navigates away mid-forge). This closes the M14 UI desync where
+  // the server kept compiling after the Forge page was left.
+  useEffect(() => {
+    return () => {
+      const tok = cancelTokenRef.current;
+      if (tok) {
+        api.cancelBuild(tok).catch(() => {});
+        cancelTokenRef.current = '';
+      }
+      batchCancelRef.current = true;
+    };
+  }, []);
+
   if (loadingDefaults) {
     return (
       <div className="page fade-in command-deck">