docs: remove redundant lint counts

[Teakowa]

Fixes #229

• Removes redundant list-preface and registry cardinalities from durable docs and the LintRegistry doc comment.
• Leaves LintRegistry as the lint inventory owner and keeps named rule IDs, ordering, CLI flags, workflow contracts, and JSON examples explicit.
• Preserves numeric CLI, protocol, resource, and illustrative payload values.

[Teakowa]

Post-merge review — follow-up required

Atomic review complete. CI passed, the registry/list count removals are otherwise scoped correctly, but one Major (acceptance) issue remains.

docs/cli.md still encodes the same list cardinality through “both are repeatable”. Replacing “Two lint-only flags” with “The following lint-only flags ... both are repeatable” removes the numeral but preserves the synchronization obligation: adding a third repeatable lint-only flag makes the sentence stale. Rewrite without cardinality coupling, e.g. “The following lint-only flags configure the registry and are repeatable:”.

The LintRegistry doc comment, docs/README.md, core-workflow wording, stable rule IDs, CLI contracts, and illustrative JSON values are otherwise correct.

Process note: this PR was merged before independent review, with no recorded review submission, while .github#12 is still open. The implementation should have remained reviewable until the acceptance criteria were audited.