Add xurlfind3r URL discovery tool

[Copilot]

• Create xurlfind3r.yaml weapon definition file
• Validate YAML syntax with yamllint
• Build documentation with erb.rb
• Run validation script to check for warnings
• Verify the tool appears in generated README.md
• Remove auto-generated files from PR (only keep weapons/*.yaml)

Original prompt

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This section details on the original issue you should resolve

<issue_title>https://github.com/hueristiq/xurlfind3r</issue_title>
<issue_description></issue_description>

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

• Fixes https://github.com/hueristiq/xurlfind3r #151

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[hahwul]

@copilot weapons 하위에 yaml 파일만 추가하세요.

[Copilot]

@copilot weapons 하위에 yaml 파일만 추가하세요.

Done. Removed auto-generated files from the PR. Now only weapons/xurlfind3r.yaml is included. (commit: 1a41c5f)