feat: add repository pattern, service layer architecture, and scheduler management

- Implement repository pattern for data access layer
- Add comprehensive service layer for business logic
- Create scheduler management system with health monitoring
- Add bounded buffer utility for memory management
- Enhance security audit logging with retention policies

app/dashboard/company/page.tsx

@@ -15,7 +15,7 @@ export default function CompanySettingsPage() {
   const csvUsernameId = useId();
   const csvPasswordId = useId();
   const { data: session, status } = useSession();
-  const [_company, setCompany] = useState<Company | null>(null);
+  const [, setCompany] = useState<Company | null>(null);
   const [csvUrl, setCsvUrl] = useState<string>("");
   const [csvUsername, setCsvUsername] = useState<string>("");
   const [csvPassword, setCsvPassword] = useState<string>("");

app/dashboard/overview/page.tsx

@@ -470,7 +470,7 @@ function DashboardContent() {
   const { data: session, status } = useSession();
   const router = useRouter();
   const [metrics, setMetrics] = useState<MetricsResult | null>(null);
-  const [company, _setCompany] = useState<Company | null>(null);
+  const [company] = useState<Company | null>(null);
   const [refreshing, setRefreshing] = useState<boolean>(false);
   const [isInitialLoad, setIsInitialLoad] = useState<boolean>(true);
 
@@ -505,27 +505,28 @@ function DashboardContent() {
         avgSessionLength: null,
         days: {},
         languages: {},
-        categories: {},
         countries: {},
         belowThresholdCount: 0,
         // Map sentiment data to individual counts
         sentimentPositiveCount:
           overviewData.sentimentDistribution?.find(
-            (s) => s.sentiment === "positive"
+            (s) => s.sentiment === "POSITIVE"
           )?.count || 0,
         sentimentNeutralCount:
           overviewData.sentimentDistribution?.find(
-            (s) => s.sentiment === "neutral"
+            (s) => s.sentiment === "NEUTRAL"
           )?.count || 0,
         sentimentNegativeCount:
           overviewData.sentimentDistribution?.find(
-            (s) => s.sentiment === "negative"
+            (s) => s.sentiment === "NEGATIVE"
           )?.count || 0,
         // Map category data to CategoryMetrics format
         ...(overviewData.categoryDistribution && {
           categories: overviewData.categoryDistribution.reduce(
             (acc, item) => {
-              acc[item.category] = item.count;
+              if (item.category) {
+                acc[item.category] = item.count;
+              }
               return acc;
             },
             {} as Record<string, number>

app/dashboard/sessions/page.tsx

@@ -32,21 +32,21 @@ interface FilterOptions {
 
 interface FilterSectionProps {
   filtersExpanded: boolean;
-  setFiltersExpanded: (_expanded: boolean) => void;
+  setFiltersExpanded: (expanded: boolean) => void;
   searchTerm: string;
-  setSearchTerm: (_term: string) => void;
+  setSearchTerm: (term: string) => void;
   selectedCategory: string;
-  setSelectedCategory: (_category: string) => void;
+  setSelectedCategory: (category: string) => void;
   selectedLanguage: string;
-  setSelectedLanguage: (_language: string) => void;
+  setSelectedLanguage: (language: string) => void;
   startDate: string;
-  setStartDate: (_date: string) => void;
+  setStartDate: (date: string) => void;
   endDate: string;
-  setEndDate: (_date: string) => void;
+  setEndDate: (date: string) => void;
   sortKey: string;
-  setSortKey: (_key: string) => void;
+  setSortKey: (key: string) => void;
   sortOrder: string;
-  setSortOrder: (_order: string) => void;
+  setSortOrder: (order: string) => void;
   filterOptions: FilterOptions;
   searchHeadingId: string;
   searchId: string;
@@ -392,7 +392,7 @@ function SessionList({
 interface PaginationProps {
   currentPage: number;
   totalPages: number;
-  setCurrentPage: (_page: number | ((_prev: number) => number)) => void;
+  setCurrentPage: (page: number | ((prev: number) => number)) => void;
 }
 
 function Pagination({