feat(KB-502): add dashboard multi-project hooks and project API routes

- Add project API routes for multi-project backend integration
- Create useProjects hook for listing and managing registered projects
- Create useCurrentProject hook for current project selection and switching
- Create useProjectHealth hook for real-time project health metrics
- Create useActivityLog hook with ActivityLogModal integration
- Add comprehensive test coverage for all hooks (useProjects, useCurrentProject, useActivityLog)
- Add test setup utilities for React Query mocking

packages/dashboard/app/hooks/useCurrentProject.ts

@@ -0,0 +1,101 @@
+import { useState, useEffect, useCallback } from "react";
+import type { ProjectInfo } from "../api";
+
+const STORAGE_KEY = "kb-dashboard-current-project";
+
+export interface UseCurrentProjectResult {
+  /** Currently selected project or null if none selected */
+  currentProject: ProjectInfo | null;
+  /** Set the current project */
+  setCurrentProject: (project: ProjectInfo | null) => void;
+  /** Clear the current project selection */
+  clearCurrentProject: () => void;
+  /** Whether we're still loading from localStorage */
+  loading: boolean;
+}
+
+/**
+ * Hook for managing the currently selected project.
+ * Persists selection to localStorage and validates the project still exists.
+ */
+export function useCurrentProject(availableProjects: ProjectInfo[]): UseCurrentProjectResult {
+  const [currentProject, setCurrentProjectState] = useState<ProjectInfo | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  // Load from localStorage on mount
+  useEffect(() => {
+    try {
+      const saved = localStorage.getItem(STORAGE_KEY);
+      if (saved) {
+        const parsed = JSON.parse(saved) as ProjectInfo;
+        setCurrentProjectState(parsed);
+      }
+    } catch {
+      // Ignore localStorage errors
+    } finally {
+      setLoading(false);
+    }
+  }, []);
+
+  // Validate project still exists and persist to localStorage
+  useEffect(() => {
+    if (loading) return;
+
+    if (currentProject) {
+      // Validate project still exists in available projects
+      const stillExists = availableProjects.some((p) => p.id === currentProject.id);
+      if (!stillExists && availableProjects.length > 0) {
+        // Project was unregistered - clear selection and default to first active
+        const firstActive = availableProjects.find((p) => p.status === "active");
+        setCurrentProjectState(firstActive || availableProjects[0] || null);
+        return;
+      }
+      
+      // Persist to localStorage
+      try {
+        localStorage.setItem(STORAGE_KEY, JSON.stringify(currentProject));
+      } catch {
+        // Ignore localStorage errors
+      }
+    } else if (availableProjects.length > 0) {
+      // No selection but projects available - default to first active
+      const firstActive = availableProjects.find((p) => p.status === "active");
+      if (firstActive) {
+        setCurrentProjectState(firstActive);
+      }
+    }
+  }, [currentProject, availableProjects, loading]);
+
+  const setCurrentProject = useCallback((project: ProjectInfo | null) => {
+    setCurrentProjectState(project);
+    if (project) {
+      try {
+        localStorage.setItem(STORAGE_KEY, JSON.stringify(project));
+      } catch {
+        // Ignore localStorage errors
+      }
+    } else {
+      try {
+        localStorage.removeItem(STORAGE_KEY);
+      } catch {
+        // Ignore localStorage errors
+      }
+    }
+  }, []);
+
+  const clearCurrentProject = useCallback(() => {
+    setCurrentProjectState(null);
+    try {
+      localStorage.removeItem(STORAGE_KEY);
+    } catch {
+      // Ignore localStorage errors
+    }
+  }, []);
+
+  return {
+    currentProject,
+    setCurrentProject,
+    clearCurrentProject,
+    loading,
+  };
+}