fix: close the review findings on the issue wave

Ported from d719fb77 (#1717); the hatch draw-order, PDF and
recovery-settle hunks stay out (main owns those paths).

- La16 was still billed at 4 B/px: the no-conversion special case
  keyed on native_bpp == 4, which La16 also is — but only Rgba8 is a
  real move in into_rgba8, so La16's decode peak is 8. The case now
  keys on the color type, and a table test pins every layout's peak
  (plus GIF's screen+frame 8) so the accounting can't silently drift.
- json_values_match: an integer beyond f64 precision no longer matches
  a float it merely rounds onto; a mixed pair matches only when the
  float is whole and converts back to exactly that integer (also the
  fuzz finding of 9262d63f).
- ocs-control.js resolves `ready` with the API object instead of
  window.ocsControl, which is still undefined when the bridge already
  exists as the script runs (built before the first settle, avoiding
  the temporal-dead-zone throw of a later const); DATALINK on web says
  the typed path is superseded by the picker instead of silently
  discarding it.

(cherry picked from commit d719fb77)

web/ocs-control.js

@@ -20,8 +20,12 @@
 
   let readyResolve;
   const ready = new Promise(resolve => { readyResolve = resolve; });
+  // Built before the first settle() can run (`request` is a hoisted
+  // function declaration): `ready` resolves with this object even when the
+  // bridge already exists as the script runs.
+  const apiObject = {ready, request};
   const settle = () => {
-    readyResolve(window.ocsControl);
+    readyResolve(apiObject);
     window.dispatchEvent(new Event("ocs-ready"));
   };
   const poll = setInterval(() => {
@@ -68,5 +72,5 @@
     return reply;
   }
 
-  window.ocsControl = {ready, request};
+  window.ocsControl = apiObject;
 })();