docs(service-analytics): retract the "more tightly than the proxy" clause from the case-exactness suite header

The round-1 contract review measured that clause false: FOLD_PER_DIALECT
inspects the COLUMN side only, so a one-sided column fold on the postgres /
unknown arm leaves this file green (exit 0, 14 passed) where the pre-fix
`LIKE translate($1,` pin caught it. The PR body and the changeset were
corrected in round 2; this source header was not, and a PR body cannot reach
someone who opens this suite six months from now.

The header now carries the two halves the PR body already states: tighter on
family separation (the four collapse mutations the review drove all went red
here), looser on both-sides folding, plus the cross-reference that
icontains-dialect-sql.test.ts holds the verbatim postgres / unknown byte pin
for that second case. Concluded as not net-weakened across the two files,
never as a strict tightening.

Comment-only, proven two ways with firing controls: every added and removed
diff line is a comment line (28 added, 8 removed, 0 non-comment; four real
code lines fed to the same filter classify as CODE), and the file transpiled
with removeComments is byte-identical to its 711db06 blob (sha256/16
941867ad0f3e45a7, 14888 bytes on both sides, while injecting one code line in
memory moves that hash). The other seven files this PR touches are untouched:
git hash-object equals the 711db06 blob for each.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XpTx2tbq3pZRYAdoGt6E6Y

Author: claude

packages/services/service-analytics/src/__tests__/text-operator-case-exactness.test.ts

@@ -72,14 +72,34 @@
  * which it no longer is.
  *
  * ⛔ It was therefore neither deleted nor loosened — it was re-aimed at the
- * property itself, which is now pinned DIRECTLY and more tightly than the proxy
- * ever did (`$icontains and the case-EXACT family stay two constructs…`
- * below): on each dialect, `$icontains` and `$contains` must compile to
- * DIFFERENT text, and `$contains` must carry no fold. That discriminates
- * against the collapse in both directions, where dialect-invariance only
- * discriminated against one. The row sets that make it more than a text
- * comparison are executed in `icontains-dialect-sql.test.ts`, which owns the
- * `$icontains` half of the family from here on.
+ * property itself, pinned DIRECTLY (`$icontains and the case-EXACT family stay
+ * two constructs…` below): on each dialect, `$icontains` and `$contains` must
+ * compile to DIFFERENT text, and `$contains` must carry no fold.
+ *
+ * ⛔ That re-aiming is NOT a strict tightening. An earlier revision of this
+ * header claimed it was ("more tightly than the proxy ever did"); #15780's
+ * contract review measured that claim false, so it is retracted here. What is
+ * true has two halves:
+ *
+ *   - **TIGHTER on family separation.** The re-aimed pin discriminates against
+ *     the collapse in BOTH directions, where dialect-invariance only caught
+ *     one. Named measured set: the four collapse mutations that review drove —
+ *     the fold leaking onto `$contains`, `$contains`' bare construct handed to
+ *     `$icontains`, and the two read-scope directions (drop the fold there /
+ *     hand it to `$contains` there). This file went red on all four.
+ *   - **LOOSER on both-sides folding.** `FOLD_PER_DIALECT` below inspects the
+ *     COLUMN side only. So the mutation that folds the column but leaves the
+ *     comparand UNFOLDED on the `postgres` / `unknown` arm slips PAST this file
+ *     — measured green there, exit 0 and 14 passed — where the pre-#15780
+ *     `LIKE translate($1,` pin would have caught it.
+ *
+ * That second case is held instead by `icontains-dialect-sql.test.ts`, which
+ * pins the `postgres` / `unknown` arm's emitted SQL and bound params VERBATIM,
+ * and which does go red on that same mutation. ⇒ Across the two files the
+ * ratchet is NOT net-weakened; within THIS file alone it is not a strict
+ * tightening. ⛔ Neither claim may be restated as "strictly tighter". The row
+ * sets that make any of this more than a text comparison are executed in that
+ * same suite, which owns the `$icontains` half of the family from here on.
  *
  * Escaping (#5567) is unchanged for every `LIKE` arm; the GLOB arm brings its
  * OWN escaped character class (`*`, `?`, `[`), which is why the second fixture