fix: reject negative page-size values in list commands

[Sypher845]

Fixes #627
Previously, negative page-size values (e.g., --page-size -1) were accepted without validation. This fix adds validation to reject negative values.

Affected commands:

• project list
• user list
• repository list
• schedule list
• registry list
• quota list
• replication policies list
• replication executions list
• artifact list
• labels list
• instance list
• project member list
• robot list
• project robot list
• logs (not a list command, but it also has the page-size flag.)

[codecov]

Codecov Report

❌ Patch coverage is 0% with 52 lines in your changes missing coverage. Please review.
✅ Project coverage is 7.15%. Comparing base (60ad0bd) to head (908492f).
⚠️ Report is 83 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/harbor/root/logs.go	0.00%	6 Missing and 1 partial ⚠️
cmd/harbor/root/instance/list.go	0.00%	6 Missing ⚠️
cmd/harbor/root/robot/list.go	0.00%	6 Missing ⚠️
cmd/harbor/root/project/logs.go	0.00%	4 Missing ⚠️
cmd/harbor/root/project/member/list.go	0.00%	4 Missing ⚠️
cmd/harbor/root/project/robot/list.go	0.00%	4 Missing ⚠️
cmd/harbor/root/quota/list.go	0.00%	3 Missing ⚠️
cmd/harbor/root/artifact/list.go	0.00%	2 Missing ⚠️
cmd/harbor/root/labels/list.go	0.00%	2 Missing ⚠️
cmd/harbor/root/project/list.go	0.00%	2 Missing ⚠️
... and 6 more

Additional details and impacted files

@@            Coverage Diff            @@
##             main    #631      +/-   ##
=========================================
- Coverage   10.99%   7.15%   -3.85%     
=========================================
  Files         173     260      +87     
  Lines        8671   12895    +4224     
=========================================
- Hits          953     922      -31     
- Misses       7612   11865    +4253     
- Partials      106     108       +2     

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[qcserestipy]

Thank you for your contribution. The over all implementation already looks good. To make this PR complete please also take care of missing list commands such as:

• instance list
• project member list
• robot list
• project robot list
• logs (not a list command, but it also has the page-size flag.)

[Sypher845]

@qcserestipy added the check to the remaining commands. Please take a look.

[qcserestipy]

@Sypher845 Looks nice, thank you!