feat: add Validator option for additional argument validation

[kazeburo]

PR Type

Enhancement, Tests, Documentation

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Description

• Add post-parse argument validation hook

• Return UNKNOWN when validation fails

• Test validator behavior for shipper execution

• Document validator usage and option

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Diagram Walkthrough

flowchart LR
  Parse["Parse command-line arguments"]
  Validate["Run configured validator"]
  Run["Execute Run method"]
  Unknown["Print error and return UNKNOWN"]
  Parse -- "parsed arguments" --> Validate
  Validate -- "validation succeeds" --> Run
  Validate -- "validation fails" --> Unknown

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File Walkthrough

	Relevant files
Enhancement	flagrun.go Add post-parse validator option and execution                        flagrun.go Add Validator func([]string) error to Flagrun. Add Validator(...) functional option. Invoke validation after successful parsing and required-argument checks. Print validation errors and return UNKNOWN. +15/-0
Tests	flagrun_shipper_test.go Test shipper validator failure handling                                    flagrun_shipper_test.go Add a validation flag and validator method to testShipper. Verify failed validator output returns UNKNOWN. Assert validation errors are written to stderr. +20/-0
Documentation	README.md Document validator option usage and behavior                          README.md Document flagrun.Validator in Japanese. Add a complete port-validation usage example. Clarify validation timing, error behavior, and supported entry points. Add the option to the configuration table. +43/-0
Formatting	go.mod Reorganize module dependency declarations                                go.mod Reorganize direct and indirect dependency declarations. Keep existing dependency versions unchanged. +5/-4

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

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⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Broken example The new example calls os.Exit but does not import os, so users cannot compile it as documented. Add the missing os import. import ( "fmt" "github.com/monitoring-forge/flagrun" )

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