Restore queue_max and queue_usage metrics to /api/stat/app endpoint

[Copilot]

Adds queue_max and queue_usage metrics back to the /api/stat/app endpoint as requested in issue #831.

Changes Made

• Added fields to status.App struct: QueueMax (int64) and QueueUsage (uint64)
• Updated appStatusHandler: Now accepts config parameter to expose cfg.Core.QueueNum as queue_max and calculates queue_usage as pending tasks (submitted - completed)
• Updated tests: Enhanced TestAPIStatusAppHandler to verify the new fields are present and valid
• Updated documentation: Added the new fields to the README example for /api/stat/app endpoint response
• Added to .gitignore: Include gorush binary to prevent accidental commits

Implementation Details

• queue_max returns the configured maximum queue capacity from cfg.Core.QueueNum (default: 8192)
• queue_usage is calculated as submitted_tasks - (success_tasks + failure_tasks), representing the number of tasks currently pending in the queue
• All calculations use uint64 arithmetic to prevent integer overflow
• The implementation maintains backward compatibility by only adding new fields to the existing JSON response

Example Response

{
  "version": "v1.18.9",
  "queue_max": 8192,
  "queue_usage": 0,
  "busy_workers": 0,
  "success_tasks": 150,
  "failure_tasks": 5,
  "submitted_tasks": 155,
  ...
}

Testing

• ✅ Build succeeds with no compilation errors
• ✅ All tests pass including the updated test for the new fields
• ✅ Code rebased cleanly on latest master (commit 41b2021)
• ✅ README conflicts resolved after major documentation rewrite

Fixes #831

Original prompt

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This section details on the original issue you should resolve

<issue_title>queue_usage and queue_max</issue_title>
<issue_description>Hello, I was still using an old version of gorush that used to return queue_max and queue_usage in the /api/stat/app endpoint which helped me monitor internal queue usage

In the new gorush version I'm running these metrics are not sent anymore in the /api/stat/app response, is there any specific reason for that?

Thank you</issue_description>

Comments on the Issue (you are @copilot in this section)

@appleboy @jean-kesrewani What is your gorush version? @appleboy @jean-kesrewani For the new version part, I am thinking about how to add it.

• Fixes queue_usage and queue_max #831

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[appleboy]

@copilot, please fix the conflicts.

[Copilot]

@copilot, please fix the conflicts.

The conflicts have been resolved by rebasing the branch onto v1.19.2 (commit 414262c). All changes are intact and the build succeeds.

[appleboy]

@copilot You need to update the master branch and fix the conflicts.

[Copilot]

@copilot You need to update the master branch and fix the conflicts.

I've successfully rebased the changes onto the latest master branch (commit 41b2021). The code changes are complete and the build succeeds. However, the automated push process is encountering conflicts due to the divergent histories between the old PR branch and the newly rebased commits.

The changes are ready in commit 9aa2d9d which includes:

• Add queue_max and queue_usage fields to /api/stat/app endpoint
• Update README with the new fields
• All code properly rebased on top of latest master

Could you please force-push or close and reopen the PR to accept these changes? Alternatively, I can create a fresh PR from a new branch if that's preferred.