refactor: simplify DutyTimelineCard component by removing TooltipProvider and Tooltip

- Removed TooltipProvider and Tooltip components from DutyTimelineCard, streamlining the button interaction for displaying contact information.
- Updated the button implementation to directly handle the click event, enhancing code clarity and reducing complexity.

webapp-next/src/components/duty/DutyTimelineCard.tsx

@@ -15,12 +15,6 @@ import {
 import { cn } from "@/lib/utils";
 import { ContactLinks } from "@/components/contact/ContactLinks";
 import { Button } from "@/components/ui/button";
-import {
-  Tooltip,
-  TooltipContent,
-  TooltipTrigger,
-  TooltipProvider,
-} from "@/components/ui/tooltip";
 import type { DutyWithUser } from "@/types";
 import { Phone, ArrowLeft } from "lucide-react";
 
@@ -120,29 +114,20 @@ export function DutyTimelineCard({ duty, isCurrent }: DutyTimelineCardProps) {
             {duty.full_name}
           </span>
           <span className="text-[0.8rem] text-muted row-start-3">{timeStr}</span>
-          <TooltipProvider delayDuration={300}>
-            <Tooltip>
-              <TooltipTrigger asChild>
-                <Button
-                  ref={frontBtnRef}
-                  type="button"
-                  variant="ghost"
-                  size="icon"
-                  className="absolute right-2 top-1/2 -translate-y-1/2 size-9 rounded-full bg-surface text-accent hover:bg-accent/20"
-                  aria-label={t("contact.show")}
-                  onClick={() => {
-                    setFlipped(true);
-                    setTimeout(() => backBtnRef.current?.focus(), 310);
-                  }}
-                >
-                  <Phone className="size-[18px]" aria-hidden />
-                </Button>
-              </TooltipTrigger>
-              <TooltipContent side="left" sideOffset={8}>
-                {t("contact.show")}
-              </TooltipContent>
-            </Tooltip>
-          </TooltipProvider>
+          <Button
+            ref={frontBtnRef}
+            type="button"
+            variant="ghost"
+            size="icon"
+            className="absolute right-2 top-1/2 -translate-y-1/2 size-9 rounded-full bg-surface text-accent hover:bg-accent/20"
+            aria-label={t("contact.show")}
+            onClick={() => {
+              setFlipped(true);
+              setTimeout(() => backBtnRef.current?.focus(), 310);
+            }}
+          >
+            <Phone className="size-[18px]" aria-hidden />
+          </Button>
         </div>
         {/* Back */}
         <div