v0.6.36

pgRDF 0.6.36 — capability custody

SHACL Core coverage 17 -> 47 probes behind a completeness gate that fails when
a spec-listed feature has no probe; pgrdf.shacl_capability() so the enforcement
set is a query rather than a test artefact; the SHACL path literal fix pinned
from a fork ahead of its upstream release; and the pgrdf-mode union fix.

Both refusal tables are now empty -- measured, not assumed.

0.6.35 was cut and refused by the release gate (META.json unbumped); versions
are never reused, so this content ships as 0.6.36.

Gate: pre-tag-check PASS, fmt clean, clippy -D warnings clean, 408 pgrx / 0,
regression 101/0, w3c-sparql 53/0, w3c-shacl 25/0, completeness 47/47,
path matrix 17 cells / 0 defective.

Full Changelog: v0.6.35...v0.6.36