Prepare FlashcardKit 0.2.0

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Summary

• set the package release version to 0.2.0
• document ordered stages, progressive sessions, and reusable three-choice round plans in the changelog
• update the README installation example to the new additive API release

Validation

• strict Swift format
• swift test (57 tests, 7 suites)
• swift build
• evaluated package manifest
• AgentGuidelines 0.0.34 consumer/provenance validation
• Markdown wrapping audit
• DocC generation
• git diff --check

Release

After exact-head approval, green CI, and merge, publish GitHub release/tag 0.2.0 and verify its release workflow before updating WortJagd.