fix(issue): Replace stopwatch toggle with explicit start/stop actions (#34818)

This PR fixes a state de-synchronization bug with the issue stopwatch,
it resolves the issue by replacing the ambiguous `/toggle` endpoint
with two explicit endpoints: `/start` and `/stop`.

- The "Start timer" button now exclusively calls the `/start` endpoint.
- The "Stop timer" button now exclusively calls the `/stop` endpoint.

This ensures the user's intent is clearly communicated to the server,
eliminating the state inconsistency and fixing the bug.

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/web.go

@@ -1253,7 +1253,8 @@ func registerWebRoutes(m *web.Router) {
 					m.Post("/add", web.Bind(forms.AddTimeManuallyForm{}), repo.AddTimeManually)
 					m.Post("/{timeid}/delete", repo.DeleteTime)
 					m.Group("/stopwatch", func() {
-						m.Post("/toggle", repo.IssueStopwatch)
+						m.Post("/start", repo.IssueStartStopwatch)
+						m.Post("/stop", repo.IssueStopStopwatch)
 						m.Post("/cancel", repo.CancelStopwatch)
 					})
 				})