feat: add initial project setup with core PDF tools and utilities

- Implement core PDF manipulation tools (split, merge, convert, etc.)
- Add state management and UI utilities
- Set up build configuration with Vite and TailwindCSS
- Include essential dependencies for PDF processing
- Add gitignore and basic project configuration files

src/js/state.ts

@@ -0,0 +1,16 @@
+export const state = {
+    activeTool: null,
+    files: [],
+    pdfDoc: null,
+    pdfPages: [],
+    currentPdfUrl: null,
+};
+
+// Resets the state when switching views or completing an operation.
+export function resetState() {
+    state.activeTool = null;
+    state.files = [];
+    state.pdfDoc = null;
+    state.pdfPages = [];
+    document.getElementById('tool-content').innerHTML = '';
+}