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

[jskong1124]

This PR fixes a state desynchronization bug with the issue stopwatch.

Problem

The current stopwatch operates on a toggle mechanism. This leads to incorrect behavior when a user interacts with stopwatches for different issues across multiple browser tabs.

Steps to reproduce:

1. Open Issue A in Tab 1 and start the timer. The UI correctly shows a "Stop" button.
2. Open Issue B in Tab 2 and start the timer. The server correctly stops the timer for Issue A and starts it for Issue B.
3. Return to Tab 1. The UI still shows a "Stop" button for Issue A, even though its timer is already stopped on the server.
4. Clicking this "Stop" button sends a toggle request, which the server interprets as a "Start" command, causing the timer to start again unexpectedly.

Solution

This PR 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.

Before (Bug in action)

After (Fix applied)

[silverwind]

Good change. Please also update the integration tests:

--- FAIL: TestViewTimetrackingControls (0.92s)
    --- FAIL: TestViewTimetrackingControls/Exist (0.19s)
        testlogger.go:61: 2025/06/23 07:21:55 HTTPRequest [I] router: completed GET /user/login for test-mock:12345, 200 OK in 7.3ms @ auth/auth.go:184(auth.SignIn)
        testlogger.go:61: 2025/06/23 07:21:56 HTTPRequest [I] router: completed POST /user/login for test-mock:12345, 303 See Other in 9.1ms @ auth/auth.go:197(auth.SignInPost)
        testlogger.go:61: 2025/06/23 07:21:56 HTTPRequest [I] router: completed GET /user2/repo1/issues/1 for test-mock:12345, 200 OK in 152.1ms @ repo/issue_view.go:317(repo.ViewIssue)
        testlogger.go:61: 2025/06/23 07:21:56 HTTPRequest [I] router: completed POST /user2/repo1/issues/1/times/stopwatch/toggle for test-mock:12345, 404 Not Found in 2.0ms @ <autogenerated>:1(WebNotFound)
        timetracking_test.go:53: Response:  Not found.
            
        timetracking_test.go:53: 
            	Error Trace:	/home/runner/work/gitea/gitea/tests/integration/integration_test.go:351

[jskong1124]

Yep! I've updated the integration tests and pushed again

[lunny]

It's still using toggle on the right top bar.

[jskong1124]

Thanks! missed that part. fixed it and pushed the update.

[wxiaoguang]

Thank you for the PR. It's great to split the "toggle" to "start/stop".

When I was reviewing the code, I found another strange behavior: "start(create)" will always stop the existing stopwatch. It would cause problem when users open 2 pages for the same issue, and they have 2 "start timer" buttons.

Then I started to fix the problem, then I found more problems in legacy code .... so my commits contain more changes than I thought ...... I also added more tests to clarify these functions' behaviors.

Do the new changes look good to you?

[jskong1124]

Wow, thanks so much for the detailed refactoring, @wxiaoguang. This was a great learning experience for me!
I hadn't even thought about the edge case of starting a timer on the same issue from different pages. Your approach makes a lot of sense, and I learned a lot from how you tackled it.

The changes look solid. LGTM!