docs: add DocC site, SDK docs hygiene, and linting

[MarcoDotIO]

Summary

• add a Swift-DocC catalog and GitHub Pages deployment workflow for the SDK docs site
• keep public repo docs SDK-focused and move parity/roadmap material into internal-docs
• add SwiftLint plus broad public API doc comments and examples across the Swift modules

Validation

• swift build -Xswiftc -warnings-as-errors
• swift test
• Scripts/lint-swift.sh
• Scripts/build-docs-site.sh
• Scripts/check-networking-concurrency.sh
• docker run --rm -v "/private/tmp/OpenClawKit-release-push.YLVbqc:/workspace" -w /workspace swift:6.2 Scripts/build-linux-runtime.sh
• docker run --rm -v "/private/tmp/OpenClawKit-release-push.YLVbqc:/workspace" -w /workspace swift:6.2 Scripts/check-networking-concurrency.sh
• docker run --rm -v "/private/tmp/OpenClawKit-release-push.YLVbqc:/workspace" -w /workspace swift:6.2 Scripts/test-linux-runtime.sh