chore(storage,workspace): gates — coverage, catalogs, bilingual note

- Per-file 100% coverage across the five new packages (invariant
  companion suites, failure-injection negatives, lifecycle and
  malformed-medium branches).
- Canonical README Model Experience / Known Limitations sections; new
  storage/ and workspace/ group READMEs; packages/README.md rows (budget
  ceiling raised 760 → 790 for the two new groups).
- Cordis catalog/type-link registrations, service-role classification,
  and regenerated catalogs/graphs for the new services and events.
- Agent Note: English body + i18n pairing record; design-sketch fences
  opted out of doc-typecheck as ignore-check.
- Two exactOptionalPropertyTypes/discriminant fixes in new tests.

doc-sync (24 gates), typecheck, hygiene, and the five-package suite
(92 tests) all pass.

packages/storage/storage-json/src/unit.ts

@@ -14,7 +14,13 @@ import { writeAtomic } from './atomic.ts'
 import { parse, serialize } from './format.ts'
 import type { UnitState } from './format.ts'
 
-/** Open (load or lazily create) one unit backed by `path`. */
+/**
+ * Open (load or lazily create) one unit backed by `path`.
+ * @param descriptor - Static identity and shape of the unit.
+ * @param path - Absolute unit file path under the backend root.
+ * @param onClose - Backend callback releasing the unit's open-slot.
+ * @returns the opened unit.
+ */
 export async function openJsonUnit(
   descriptor: KvUnitDescriptor,
   path: string,