0.5.6 — an auditable result, and a Mac as a real solver host

The release that makes a result auditable and a Mac a real solver host. Every tool
call is now journalled, so a session can be exported as a Python script that
regenerates the model and its simulations. The script checks every number a solve
reported, names the exact solver binary and version that produced it, and diffs the
input deck the solver was handed. With one setting the journal also goes to disk,
where it outlasts the session. On macOS, YADE, Elmer, openEMS and Bempp now run
through the container substrate alongside OpenFOAM. That container is a new
runtime-only solver image, about a fifth of the CI image's download, signed and
scanned, and it records which solvers it contains so doctor cannot report a missing
one as ready. There is also a new explicit impact solver and one checked against an
exact closed-form answer, CalculiX that no longer blocks the MCP channel, and fixes to
STEP export and to the openEMS gate that change what a user gets back.

Added

• Session journal and session_transcript. Every MCP tool call is recorded in
  memory with its full arguments and a trimmed result. session_transcript returns the
  session as a Python script that regenerates the model, drawings and simulations
  through the same tools in a fresh worker. Handles become variables, job polls
  become s.wait(job), and absolute paths become WORKDIR-relative. Inspection
  calls are dropped unless a later call used them, but analysis calls (hand calcs,
  FEM, every *_submit) never are. Each analysis result is checked whole: every
  number becomes s.check, and its verdict fields (fidelity, correlation, solver,
  gate pass) become s.expect. A replay that reaches a different solver therefore
  stops at that step rather than returning a plausible figure. The script opens
  with a PROVENANCE record (AnkusDrive, FreeCAD, platform, substrate, and every
  solver the session reached with its path, substrate and probed version).
  s.provenance() re-resolves that record on the replaying machine and prints what
  moved. run_script code is carried verbatim with its SHA-256
  (#407,
  #408,
  #409,
  #410,
  #433).
• Durable journal and journal_export, opt-in. ANKUSDRIVE_JOURNAL_DIR (or
  journal_dir in config.toml) writes one JSONL file per session: an environment
  header, then one line per call with a SHA-256 of the full result. Old files are
  removed oldest-first past 50 files or 512 MB, never the live session's file.
  ANKUSDRIVE_JOURNAL_REDACT=1 hashes paths and names, but never run_script code; a
  redacted journal can be checked but not replayed. journal_export and
  ankusdrive journal list|export turn a past session's file into the same record
  session_transcript gives. Off by default
  (#433).
• Every solve records the deck it was handed. A job snapshots its case (file
  list plus per-file SHA-256) when its first solver step launches, and the result
  carries it as deck next to case_dir. On replay, s.deck(...) reports whether the
  input matched, so a drifted number is attributed to the problem or to the solver
  (#437).
• Impact dynamics: impact_dynamics_submit (a CalculiX *DYNAMIC penalty-contact
  solve) and bar_impact (the closed form). They are gated against St-Venant's exact
  elastic bar striking a rigid wall (face stress ρ·c₀·v₀, contact time 2L/c₀,
  rebound at the strike speed) and against the plastic-wave cap past yield. This was
  the last unbuilt row of docs/SIMULATION_NEXT.md
  (#311).
• fem_run_submit runs a CalculiX solve as a background job, so a long FEM run no
  longer blocks the MCP channel. fem_run stays for solves that take seconds
  (#308).
• YADE, Elmer, openEMS and Bempp run through the container substrate
  (ANKUSDRIVE_SUBSTRATE=container), probed inside the running container with no
  exports needed. On a Mac this brings DEM, every Elmer family, full-wave EM and
  acoustic BEM in with one docker pull
  (#419).
• ghcr.io/gchen19/ankusdrive-solvers, a runtime-only solver image for the
  container substrate: 0.88 GB compressed on arm64 and 1.15 GB on amd64, against 4.5 /
  5.3 GB for the CI image. Tags: :latest/:full for every solver, and :openfoam
  for OpenFOAM alone. tools/build_solver_image.sh --solvers "…" --from-published
  builds any other set in minutes with no compile. Every image writes
  /etc/ankusdrive/solvers.json, and discovery reads it first, so a solver an image
  leaves out is reported as "this image does not include …", never as ready
  (#422).
• Signed, scanned solver images. Both images carry Sigstore build provenance and a
  CycloneDX SBOM, and are scanned for secrets and fixable critical CVEs.
  scripts/verify-container-image.sh and ankusdrive doctor --verify-image check an
  image against this repository's workflow. doctor also reports a container that
  runs with more privilege than the documented docker run grants
  (#423).
• scripts/install-solvers.sh elmer source-builds a pinned Elmer on Linux (including
  arm64, which has no package) and on macOS
  (#384).
• pocket and hole accept strict=True, which escalates their "removed everything"
  and "removed nothing" warnings to errors, as boolean_op already did
  (#287).
• solve_capabilities reports the case root, with its live size and the retention
  policy (#437).

Changed

• Solver case directories live under one root with a stated retention. Cases are
  written to <system temp>/ankusdrive-cases (ANKUSDRIVE_CASE_ROOT moves it). Past
  64 directories or 4 GB, the oldest are removed first, but never one written in the
  last hour (ANKUSDRIVE_CASE_KEEP / _MAX_GB / _GRACE_S;
  ANKUSDRIVE_KEEP_SCRATCH=1 keeps everything). A directory you pass in is never
  touched. Directories left loose in the system temp dir by earlier versions are not
  moved or cleaned up
  (#437).
• Under the container substrate, an override the container cannot use is now
  reported instead of replaced. A stale ANKUSDRIVE_ELMER_PATH, ANKUSDRIVE_YADE,
  ANKUSDRIVE_OPENEMS_PYTHON or ANKUSDRIVE_BEMPP_PYTHON, or a host install's path
  in config.toml, now leaves that family not ready. The hint names the variable and the
  image's own copy that clearing it would give. Check ankusdrive doctor after
  upgrading if you moved a Mac from a native or Multipass setup
  (#443,
  #422).
• em_fullwave is gated on the solved field. The documented fc_ratio gate never
  read the FDTD field: openEMS computes the port's beta analytically, so even a
  truncated run passed. A new alpha_ratio gate fits the solved field's decay below
  cutoff against the exact value, and the dipole mesh is now resolved finely enough
  for its resonance to be meaningful
  (#398–#403).
• docs/SOLVERS_MACOS.md and docs/MACOS.md no longer call the container-reachable
  families unavailable, and recommend the solver image over the CI image. The macOS
  Gatekeeper caveat is retired: a server Claude Desktop launches from a never-run,
  notarized FreeCAD passes without a dialog, and doctor diagnoses a blocked boot
  (#310,
  #432).

Fixed

• STEP/IGES export of an assembly wrote an empty file and reported success.
  Exporting an App::Part (links or plain features) produced 1,640 bytes with no
  faces, and release_package shipped that to vendors. The resolved shape is now
  exported, and an export with no geometry is an error
  (#434).
• export_shape with no object exported the first shape in the document (after a
  cut, the consumed base) instead of the final one. It also crashed once an FEM mesh
  existed. Both are fixed at every site that walked the document the same way
  (#414).
• A transcript replay now lists a prepared case_dir / sif / case / deck under
  Prerequisites instead of pointing at a directory nobody was asked to create
  (#437).
• A native install's config.toml path is no longer sourced inside a container that
  lacks it, which used to fail with blockMesh: command not found
  (#422).
• pocket/hole no longer reject strict on the MCP surface with TypeError
  (#287).

Security

• The solver images' build inputs are pinned: CalculiX over HTTPS with a SHA-256,
  preCICE by commit, and the OpenFOAM apt repo key checked instead of piped to
  bash. The documented docker run is least-privilege (--network none,
  --cap-drop ALL, --read-only, no-new-privileges, non-root)
  (#423).