Remove unused components and models for improved maintainability

- Deleted redundant components (`AddActionButton`, `AlertBox`, `AlertStack`, `BackButton`, `CancelButton`, and `CollapsableArea`) and related files.
- Removed unused models (`Book`, `BookSerie`, `BookTables`, `Character`, and `Chapter`) to reduce codebase clutter.
- Updated project structure and references to reflect these removals.

lib/utils/quillsense.ts

@@ -0,0 +1,41 @@
+import {SessionProps} from "@/lib/types/session";
+import {Subscription} from "@/lib/types/user";
+import {getCurrentSubscription} from "@/lib/utils/user";
+
+export function getSubLevel(session: SessionProps): number {
+    let currentSub: Subscription | null = getCurrentSubscription(session?.user, 'quill-sense');
+    if (!currentSub) {
+        currentSub = getCurrentSubscription(session?.user, 'quill-trial');
+        if (!currentSub) {
+            return 0;
+        }
+    }
+    switch (currentSub?.subTier) {
+        case 1:
+            return 1;
+        case 2:
+            return 2;
+        case 3:
+            return 3;
+        default:
+            return 0;
+    }
+}
+
+export function isBringYourKeys(session: SessionProps): boolean {
+    if (!session?.user) return false;
+    const currentSub: Subscription | null = getCurrentSubscription(session?.user, 'use-your-keys');
+    return currentSub?.status || session.user.groupId <= 4;
+}
+
+export function isGeminiEnabled(session: SessionProps): boolean {
+    return session.user?.apiKeys.gemini || false;
+}
+
+export function isAnthropicEnabled(session: SessionProps): boolean {
+    return session.user?.apiKeys.anthropic || false;
+}
+
+export function isOpenAIEnabled(session: SessionProps): boolean {
+    return session.user?.apiKeys.openai || false;
+}