Make text selectable in Khoj chat modal on Obsidian

Previously the text in the Khoj chat modal couldn't be copied as it
was not selectable

Resolves #206

src/interface/obsidian/src/chat_modal.ts

@@ -98,6 +98,9 @@ export class KhojChatModal extends Modal {
             text: `${message}`
         })
 
+        // Remove user-select: none property to make text selectable
+        chat_message_el.style.userSelect = "text";
+
         // Scroll to bottom after inserting chat messages
         this.modalEl.scrollTop = this.modalEl.scrollHeight;