Remove rounded corners from dialogs and task input fields

Update DialogContent component to remove rounded corners by setting `rounded-none` class. Modify TaskFormInline component in Tasks.tsx to remove `borderRadius: '6px'` and set `borderRadius: '0px'` for various input elements and buttons. Also, change the default value of the 'assignedTo' input field from 'admin' to an empty string.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: d7bae60c-959e-464e-9a81-d3f674984466
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/d7bae60c-959e-464e-9a81-d3f674984466/JW835E1

client/src/components/ui/dialog.tsx

@@ -38,7 +38,7 @@ const DialogContent = forwardRef<
     <DialogPrimitive.Content
       ref={ref}
       className={cn(
-        "fixed left-[50%] top-[50%] z-50 grid w-full max-w-lg translate-x-[-50%] translate-y-[-50%] gap-4 border border-gray-200 bg-white p-6 shadow-xl duration-200 data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[state=closed]:slide-out-to-left-1/2 data-[state=closed]:slide-out-to-top-[48%] data-[state=open]:slide-in-from-left-1/2 data-[state=open]:slide-in-from-top-[48%]",
+        "fixed left-[50%] top-[50%] z-50 grid w-full max-w-lg translate-x-[-50%] translate-y-[-50%] gap-4 border border-gray-200 bg-white p-6 shadow-xl duration-200 data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[state=closed]:slide-out-to-left-1/2 data-[state=closed]:slide-out-to-top-[48%] data-[state=open]:slide-in-from-left-1/2 data-[state=open]:slide-in-from-top-[48%] rounded-none",
         className
       )}
       {...props}