0.5.2 — the MCP Registry listing

The release that puts AnkusDrive on the official MCP Registry. The registry proves
PyPI ownership by reading an mcp-name: token out of the README as uploaded, and
0.5.1's upload predates that token — so, as with 0.5.1's frozen project page, only a
new version can carry it. This is the first release whose tag push lists itself.

Added

• AnkusDrive is listed on the official MCP Registry
  as io.github.gchen19/ankusdrive. server.json describes the PyPI package
  (uvx ankusdrive mcp, optional ANKUSDRIVE_FREECADCMD); the README carries the
  mcp-name: ownership token the registry reads from the PyPI upload; and
  publish.yml publishes to the registry after every PyPI release, via GitHub OIDC
  with a pinned, checksum-verified mcp-publisher. A fast-lane contract test
  fails any release PR whose server.json version drifts from __version__
  (#201).

Changed

• fem_run and fem_cantilever_demo default their workdir to
  <TMPDIR>/ankusdrive_fem instead of a literal /tmp path, so the default follows
  the platform's temp directory. Callers that pass workdir see no change. The FEM
  tests now remove their CalculiX scratch dirs at exit instead of stranding
  multi-MB result files on the runners; ANKUSDRIVE_KEEP_SCRATCH=1 keeps them for
  debugging (#336).