feat: localize research reports static presentation

[gcomneno]

Summary

Completes #61 Gate 4 by localizing all static ResearchReports presentation while preserving dynamic research content and bridge semantics.

Included

• locale propagated from App to ResearchReports as a presentation-only prop;
• canonical English + deterministic Italian for page chrome, catalog/loading/error fallbacks, buttons, source label, twins filters, empty states, notes panel title and placeholders;
• static candidate marker localized in the component while preserving candidate truth semantics;
• bridge.researchCatalog() remains zero-argument and bridge.researchReport(reportId) remains locale-free;
• dynamic catalog/report content remains raw and untranslated: IDs, titles, summaries, interpretations, sources, metric labels/values/formats, table titles, column labels/keys/formats and notes;
• twins filtering predicates and filter values remain unchanged;
• tests cover EN default, explicit IT, dynamic-value exclusion from the catalog and bridge/payload parity.

Boundary

No Python application, domain, repository, bridge payload, structured report or dynamic research prose changes. No LLM/GiadaWare AI is used for static GUI localization.

Closes #61