test(system): compare Diagnostics & logs with the concept

System › Diagnostics & logs and its log cleanup review are compared with the
concept (app.js 694–695 and maintenancePlan("rotated logs")) in both themes at
1600x1100 and 390x844, with D109 and D110 (and D100 for the review) as the only
mapped differences, a 320-wide select check and a mutation check.

The fixture gains a concept seed mode (the concept's four log lines, a 1.4 MB
active log with three rotated copies, console logging off), and the plan
dialog's measureReview and mapPlanConcept move unchanged into
concept-inventory.mjs for Maintenance and this review.

The comparison found that the Database line read a report key that does not
exist (database_info.size_bytes) and so always showed "0 bytes"; it now reads
database_size_bytes, the key get_database_info() returns.

Part of #329

web/js/workspace/system-diagnostics.mjs

@@ -112,7 +112,7 @@ export function databaseText(state) {
         const check = report?.checks?.database;
         if (check?.status !== 'ok') return `Not readable: ${check?.message || 'no answer from the database'}`;
         const images = Number.isSafeInteger(check.image_count) ? check.image_count : 0;
-        return `Readable · ${sizeText(report.database_info?.size_bytes)} · ${number(images)} ${noun(images, 'image')}`;
+        return `Readable · ${sizeText(report.database_info?.database_size_bytes)} · ${number(images)} ${noun(images, 'image')}`;
     });
 }