[ZoomIt] Add datetime suffix to screenshots (#43172)

This pull request introduces an improvement to how screenshot filenames
are generated in `ZoomIt`. The main change is to ensure that each
screenshot is saved with a unique, timestamped filename, which helps
prevent accidental overwrites and keeps files sorted chronologically.

**Enhancement to screenshot filename generation:**

* Added a new implementation for `GetUniqueScreenshotFilename()` in
`Zoomit.cpp` to generate screenshot filenames using the current date and
time, following the format `"ZoomIt YYYY-MM-DD HHMMSS.png"`. This
reduces the risk of overwriting existing files and improves file
organization.<!-- Enter a brief description/summary of your PR here.
What does it fix/what does it change/how was it tested (even manually,
if necessary)? -->
## Summary of the Pull Request
This PR:

Includes an update to create unique screenshot filenames, saving the
user from having to manually type a new filename each time they save a
new screenshot in the same location.

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## PR Checklist

- [x] Closes: #43158
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
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for new binaries
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for new binaries and localization folder
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<!-- Provide a more detailed description of the PR, other things fixed,
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

## Unique filename issue

The PR fixes the user's complaint about the screenshots always being
called "zoomit" by adding a `GetUniqueScreenshotFilename()` method which
creates a unique filename based on the current date and time, e.g.
`ZoomIt 2025-11-01 004723.png`. This is consistent with other tools like
the Windows Snipping Tool and provides files which sort correctly when
ordered by name, which is not the case for files with simple numeric
suffixes.

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

Tested on a local build.

src/modules/ZoomIt/ZoomIt/Zoomit.cpp

@@ -5507,9 +5507,29 @@ auto GetUniqueRecordingFilename()
     return GetUniqueFilename(g_RecordingSaveLocation, defaultFile, FOLDERID_Videos);
 }
 
+//----------------------------------------------------------------------------
+//
+// GetUniqueScreenshotFilename
+//
+// Gets a unique file name for screenshot saves, using the current date and
+// time as a suffix. This reduces the chance that the user could overwrite an
+// existing file if they are saving multiple captures in the same folder, and
+// also ensures that ordering is correct when sorted by name.
+//
+//----------------------------------------------------------------------------
 auto GetUniqueScreenshotFilename()
 {
-    return GetUniqueFilename(g_ScreenshotSaveLocation, DEFAULT_SCREENSHOT_FILE, FOLDERID_Pictures);
+    SYSTEMTIME lt;
+    GetLocalTime(&lt);
+
+    // Format: "ZoomIt YYYY-MM-DD HHMMSS.png"
+    wchar_t buffer[MAX_PATH];
+    swprintf_s(buffer, L"%s %04d-%02d-%02d %02d%02d%02d.png",
+        APPNAME,
+        lt.wYear, lt.wMonth, lt.wDay,
+        lt.wHour, lt.wMinute, lt.wSecond);
+
+    return std::wstring(buffer);
 }
 
 //----------------------------------------------------------------------------