chore: publish KMP marketplace 0.5.1

[tgarciai]

Summary

• pin Claude Code to the immutable, clonable v0.5.1 release ref
• mirror the exact KMP 0.5.1 plugin tree for Codex
• include the selective uninstall contract and SQLite-only public wording

Provenance

• KMP main commit: ad2b26b3cdabd0e74e90233a10425503415abc16
• reviewed candidate run: 33255458764
• candidate input digest: 981f17f1084b31136613de6ca0cd54548dab0d69b693b4a3d25961f21b73af81
• local prerelease contract: 0.5.1, 13 tools, future annotated tag bound to exact KMP main
• release-ref regressions: future main binding, lightweight-tag refusal, annotated-tag acceptance

Release gate

Do not merge until v0.5.1 and its assets are public and real clean installs plus 0.4.2 updates have passed for both Claude Code and Codex without a transport substitute. This preserves the safe ordering fixed by underpass-ai/kmp#400.

Closes underpass-ai/kmp#390 follow-up release hardening.

Post-publication verification

• Annotated tag v0.5.1 peels to KMP ad2b26b3cdabd0e74e90233a10425503415abc16 and records this PR head 16d9f548d25186a65af523e4d77f10c7fb075d85.
• Release run 33258710773, distribution run 33258710782, and MCP Registry run 33258710758 completed successfully.
• GitHub Release assets, crates.io, GHCR image, Helm chart, and MCP Registry publication are green.
• Clean isolated Codex and Claude Code installs reached plugin and engine 0.5.1 with exact source-tree parity and 13 tools.
• The public 0.4.2 updater reached 0.5.1 in both hosts without a transport substitute; its pre-existing SQLite memory remained readable.
• The marketplace contract passed after publication using the literal cloneable annotated ref v0.5.1.