docs(limitations): the entropy headroom is 0.099, not 0.36 -- measured in the field

ms-ai-architect re-measured after retracting their entropy refutation (their
original finding scored whole filenames as one unit, so it was never a finding
about our rule). The retraction confirms the branch; the re-measurement produced
a number we did not have, and it goes against us.

The sharpest legitimate token in their 2400-URL corpus is a 78-character
percent-escaped lovdata title at H=4.301. That is 0.099 from the 4.4 floor where
this bullet previously implied 0.36 -- the mechanism was already ours, but the
worked example understated how thin the margin gets in real Norwegian
government paths.

Verified against our own code before recording, not reconstructed: our real
_URL_TOKEN_RE emits it as a single 78-character token, our shannon_entropy
returns 4.301, and is_ordinary_url returns False. Their three calibration
examples also reproduce to three decimals here.

Threshold stays. Their own conclusion too -- moot per URL, since the % rule
already disqualifies it before entropy is consulted.

Records the 2400-vs-2401 provenance split explicitly. The counts come from two
different harvesters over the same knowledge base and differ by one URL; the
neighbouring hex bullet cites 2401. Left unstated, a later reader would
reasonably merge them into one corpus figure, which is exactly the
prose-vs-measurement conflation this file exists to prevent.

docs/LIMITATIONS.md

@@ -169,6 +169,17 @@ items; this is the full list, each with the mechanism.
   short ones. Measured at H=4.04 — under the 4.4 floor, and moot in practice because
   the `%` rule already disqualifies the URL. It is recorded because it means the
   length floor does less work in non-ASCII paths than the calibration assumed.
+  **A field re-measurement (2026-07-31) sharpens this by roughly 3x.** The
+  highest-entropy *legitimate* token in a consumer's 2400-URL corpus is not the one
+  above but a 78-character percent-escaped lovdata title, `Fra%20%C3%A5ndsverk%20…`,
+  at H=4.301 — leaving **0.099 of headroom to the 4.4 floor, not 0.36**. Re-run here
+  through the real `_URL_TOKEN_RE` and `shannon_entropy` rather than a reconstruction:
+  our tokenizer does emit it as one 78-character token. Still moot per URL
+  (`is_ordinary_url` is False on the `%` rule) and still not a reason to move the
+  threshold — but the margin this bullet reports is much thinner than 4.04 implies.
+  Note the corpus count: 2400 is a rebuilt harvester's, where the 2401 in the next
+  bullet is the earlier run's. Same knowledge base, different scripts, one URL apart —
+  they are not interchangeable and must not be summed or quoted as one figure.
 - **Legitimate CDN content-asset ids trip the hex branch, permanently.** A ≥32-char
   hex path segment is opaque by design, and several public CMSes mint asset URLs that
   way (measured: 9 distinct on `regjeringen.no`, `ks.no`, `datatilsynet.no`). This is