Validate ECL concept references and standardise parse errors

Concept ids in ECL expressions are now checked for both Verhoeff
checksum and SNOMED CT concept partition at parse time, so malformed
ids (e.g. `< 99999999`) throw `:invalid-code` instead of silently
returning zero results. All `ex-info` ex-data thrown from parsing now
conforms to a new `::parse-error` spec with a closed `:error`
taxonomy (`:syntax-error`, `:invalid-code`, `:not-found`,
`:invalid-value`, `:not-supported`) and a uniform `:s` field. Adds a
`[5..2]`-style cardinality range check and converts the
pending/unsupported test list into data-driven cases that assert the
expected error category.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: wardle