Update main README content for v0.1.0 core specification release

[meisterware-admin]

Summary

Updated README.md to reflect the release of OpenPAKT v0.1.0 — Core Specification.

The README now clearly communicates the current specification version, clarifies the project status, and improves the explanation of how the specification relates to implementations such as the Detektor reference CLI.

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Type of change

Select all that apply:

• Specification change
• Documentation update
• Example artifact update
• Governance / repository process update
• Non-functional cleanup

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Specification classification (if applicable)

• Normative change (affects specification behaviour)
• Non-normative change (clarification, examples, wording)

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Related issue

Closes #

This PR updates project documentation to reflect the v0.1.0 Core Specification release milestone.

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What changed

Main updates to the README include:

• updated specification badge to v0.1.0
• clarified project status following the v0.1.0 Core Specification release
• removed wording indicating the project was still evolving toward v0.1
• refined description of the OpenPAKT architecture and scope
• clarified separation between the OpenPAKT specification and tool implementations
• improved explanation of the Detektor reference implementation
• updated roadmap section to reflect the current milestone progression
• update Detektor / Detektor CLI content references by adding link to GitHub Detektor repository

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Impact

This change improves:

• project clarity for new readers
• visibility of the current specification version
• understanding of OpenPAKT as a specification rather than a single tool
• credibility of the repository for security engineers and potential adopters

There are no specification behaviour changes.

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Compatibility

• Backward compatible
• Additive change
• Breaking change
• Not applicable

This PR only updates documentation and does not modify the specification itself.

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Checklist

• Change is aligned with OpenPAKT scope
• Related documentation has been updated if needed
• Examples have been updated if needed
• Compatibility impact has been considered
• This PR does not introduce unnecessary scope expansion

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Notes for reviewers

This update prepares the repository README for the OpenPAKT v0.1.0 Core Specification release.

The goal is to ensure the landing page accurately reflects the current project state and communicates the intended architecture:

OpenPAKT specification → scanner implementations (e.g., Detektor) → CI policy evaluation.