Refine required flag validation

[ncode]

Summary

• Moved required flag validation for run and cleanup commands from Cobra-level required flags to command handlers.
• run now explicitly returns clear errors when service-id or script is missing.
• cleanup now explicitly requires service-id while leaving script optional since it is not used.
• Updated command tests to validate new error messages and removed assumptions about Cobra-required flag behavior.

Verification

• go test ./cmd/...
• go test ./...

Closes: N/A

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.94%. Comparing base (d8fd2ca) to head (f8b61b9).
⚠️ Report is 20 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #34      +/-   ##
==========================================
+ Coverage   89.75%   89.94%   +0.19%     
==========================================
  Files           8        8              
  Lines         361      368       +7     
==========================================
+ Hits          324      331       +7     
  Misses         25       25              
  Partials       12       12              

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