fix(lexicon,docs): the script-tag row reversed — commons is now the sole diverger

llm-security commit 90f576f (2026-08-10) dropped the closing-</script>-tag
requirement from hybrid-xss:script-tag, matching what the guard has always had.
Both now agree in shape (no closing tag required), still not byte-identical
([^><] vs [^>]). Commons' own extracted pattern is unchanged under
behaviour-preservation, so it is the only one of the three still requiring a
closing tag — the opposite of what the divergence doc said when it was written.

injection-lexicon.json gains source_fidelity.post_extraction_drift: the
existing 83/83-at-b0de0ca claim is untouched (extraction-commit fidelity never
decays), and the new 82/83-at-b1ba1fb count carries its own commit and date so
it doesn't read as a bare, decaying "vs HEAD" claim.

Verified directly against both upstream trees this session, not relayed:
llm-security's public remote re-fetched to b1ba1fb, guard read at HEAD 0dce50f.

CHANGELOG.md

@@ -11,6 +11,22 @@ case ids, disposition semantics). Each JSON file additionally carries its own
 
 ## [Unreleased]
 
+### Added
+
+- `lexicon/injection-lexicon.json` (`0.5.1` → `0.6.0`) — `source_fidelity.post_extraction_drift`,
+  recording that `llm-security` commit `90f576f` (2026-08-10) dropped the closing-tag
+  requirement from `hybrid-xss:script-tag`'s source pattern, which this file — a frozen
+  extraction under behaviour-preservation — does not follow. `patterns_byte_identical_to_source`
+  (83, at extraction commit `b0de0ca`) is unchanged and still true; the new field adds the count
+  against `llm-security`'s later HEAD (82/83, measured against `b1ba1fb`, 2026-08-11) so a
+  consumer diffing against current upstream has a coordinate to resolve the mismatch against
+  instead of finding it unexplained. No pattern text, id, or existing key changed — additive
+  only, hence minor. Companion informative update in `docs/lexicon-port-divergence.md`, whose
+  `hybrid-xss:script-tag` row is reversed: commons is now the sole diverger of the three runtimes
+  on this one construct, not the guard.
+
+  Repository tag unaffected — no file set, key name, case id, or disposition semantics moved.
+
 ## [0.2.0] — 2026-08-11
 
 The contract gained a normative MUST, which is why this is a release rather than a