chore(release): prepare 0.5.2

[mathiasbourgoin]

Summary

• bump release metadata and runtime version to 0.5.2
• remove the miaou-core opam template that reintroduced development pin-depends
• regenerate opam package files so the release archive is opam-repository ready

Verification

• dune fmt
• dune build @ALL
• dune runtest
• dune build @install
• opam lint *.opam
• _build/default/src/miaou_runner/miaou_runner_tui_main.exe --version
• _build/default/src/miaou_runner/miaou_runner_native_main.exe --version