v3.22.0 (review fixes): the ownership reconciliation and the import guards

The suite/script ownership invariant could break silently: a suites import
with mode "replace" wiped the suites while their scripts stayed behind
(suite_id pointing at gone suites - invisible in the UI), a scripts import
with mode "replace" left every suite's member list dangling, and a script
whose suite_id disagreed with its listing suite stayed inconsistent.

- server: reconcile_scripts_to_suites() repairs the invariant - a script a
  suite lists adopts that suite (the member list is authoritative), a script
  no suite lists joins "Imported scripts"; migrate_scripts_to_suites()
  delegates to it (the startup migration is the same pass) and the suites
  import runs it after loading, so a "replace" adopts the wiped suites'
  scripts instead of losing them.
- the scripts import refuses mode "replace" while any suite still lists
  scripts (400 naming the dangling references; merge is the normal path).
- nits from the review: a legacy numeric `event` is no longer parsed as hex
  in the step summary/error check (0x0A displayed as 0x10), and an integral
  float memory quota (a JSON client's 200.0) is accepted.
- tests: the reconciliation (missing suite, listed-but-mismatched,
  idempotent), the scripts-replace guard (refused/allowed), the
  suites-replace adoption, the float quota, the numeric-event summary.
  Tests: 838 frontend + 800 Python; sw cache simple-v402.

frontend/index.html

@@ -7197,7 +7197,8 @@ function testStepSummary(step) {
 			: 'item=' + p.item_id);
 	}
 	else if (step.kind === 'event') {
-		const code = parseInt(p.event, 16);
+		// a legacy numeric event is the code itself; the editor stores hex
+		const code = (typeof p.event === 'number') ? p.event : parseInt(p.event, 16);
 		s = 'EVENT ' + (EVENT_NAMES[code] || ('0x' + String(p.event || '?')));
 		if (p.src) s += ' src=' + p.src;
 	}
@@ -8290,7 +8291,9 @@ function testStepFormError() {
 			if (problem) return problem;
 		}
 		if (step.kind === 'event') {
-			const code = parseInt(String((step.params || {}).event || ''), 16);
+			const rawEvent = (step.params || {}).event;
+			const code = (typeof rawEvent === 'number') ? rawEvent
+				: parseInt(String(rawEvent || ''), 16);
 			const cfg = EVENT_FORMS[code];
 			if (!cfg) return t('No form for this event - use the raw Envelope action.');
 			const bad = eventFormPatternError(cfg, (step.params || {}).fields || {});