Bug: Virtual apps index shows empty even when applications exist; OR API URLs contain [object Object]

[rubenvdlinde]

Symptom

`/apps/openbuilt/applications` shows "No items found" empty state.

Backend API (`GET /index.php/apps/openbuilt/api/applications`) returns hello-world correctly as JSON — the data IS there.

Browser console shows two errors:
```
GET http://localhost:8080/apps/openregister/api/schemas/[object%20Object] 404
GET http://localhost:8080/index.php/apps/openregister/api/objects/undefined/[object%20Object]?_limit=20&_page=1 404
```

The frontend store is passing a register/schema object (or undefined) where the OR API expects a string slug/id. Likely a shape mismatch between the manifest's `register` + `schema` config and what the store hooks expect.

Hypothesis

After spec C reshaped Application + ApplicationVersion, the schemas store or the CnIndexPage's data-fetch wiring is reading a no-longer-existing field. Per spec [4/8] there's now a `registerSlugForApp(appSlug, versionSlug)` that constructs `openbuilt-{slug}-{versionSlug}` — the store may be invoked before `versionSlug` resolves, producing `openbuilt-undefined-{undefined-object}`.

Repro

1. Apply PRs [1/8] refactor: split Application + ApplicationVersion (ADR-002 foundation) #58 → [8/8] fix(tests): stabilise 11 PHPUnit failures + ProductionVersionGuardListener runtime bug #65
2. Navigate to `/apps/openbuilt/applications`
3. Open DevTools network tab → see the 404s with `[object Object]` in the URL
4. Open DevTools elements → "No items found" empty state visible

Probable culprit

`src/stores/schemas.js` or wherever CnIndexPage's `register`+`schema` config gets resolved against the OR API. Check whether the page's `config.register / config.schema` are still being read as strings vs being shadowed by computed objects from the version-routing changes.

Surfaced during the morning visual smoke pass.

[rubenvdlinde]

Closed by PR #70 merge to development. Verified via visual smoke.