Add scoped desktop stock reporting for Posnic Business

[sridharkalaibala]

Stored inventory was not available through the separate Business reporting API. This adds bounded desktop stock preparation, strict partial-coverage validation, Community publication and an authenticated stock endpoint with live item ACL and branch checks. Cloud continues to read prepared snapshots only; the paired Gateway change transports them.

The scan preserves signed unit thousandths and item/branch reorder thresholds, rejects ambiguous shared balances and duplicate logical IDs, and reports unavailable coverage explicitly. The result never claims complete inventory truth. Stock data cannot overwrite daily or register summaries.

Validation: 14 stock source/preparation tests, 11 stock publication/read tests, 19 Business HTTP tests, 9 register-publication regressions and 3 cross-repository tests pass. Nine stock unit tests, 24 repository checks, relevant lint/format, runtime/declaration/attribution checks and generated API consistency pass. OpenAPI retains 14 existing ambiguity warnings.

Depends on the register-summary stack in #1020. Companions: Gateway #27 and mobile #16. Concurrent receiving/sync reconciliation, stock alerts and physical-device qualification remain open. No server deployment or production-readiness claim.

[sridharkalaibala]

The complete Business companion stack, including this change, is integrated into develop through #1023. All checks, including CodeQL, passed before merge. Closing this superseded stacked PR.