New `attach-bsdl <module> <part> <file.bsd>` command: parse via BsdlModel,
apply_bsdl() onto the part, store the path on Part::bsdl_path, report bound/
unbound. Persist a `B\t<path>` line under the part; on restore, re-parse and
re-apply each attached model (the .bsd path is persisted, not the derived
pin specs). Round-trip covered by test_bsdl_apply.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Link libbsdl dynamically (add_subdirectory ../libbsdl, overridable via
-DBSDL_DIR). New BsdlModel wraps the C ABI and reduces a parsed .bsd to
essim's pin vocabulary; apply_bsdl() binds each port to a Pin (by name, then
by physical pad) and sets its spec: direction, function (TAP role / power /
ground / signal), pad, and source = Bsdl.
This feeds the PinSpec fields from P1, so verify's existing power/ground
placement pass now lights up for BSDL-modelled parts. Covered by
test_bsdl_apply (name + pad binding, TAP roles, linkage classification).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
