Frontend shared contracts

This package exports frontend-safe types, runtime schemas and template-variable extraction. redactFields(value, sensitiveFields, replacement?) recursively copies JSON-like data, replacing explicitly selected keys without mutating the input. Field matching is case-sensitive; the default replacement is [Redacted]. Consumers retain sensitive-field lists and reporter hooks.

The redaction primitive has no Node, NestJS or backend dependencies. It expects JSON-like objects and arrays, matching error-report payloads. Its source contracts are in src/redact-fields.spec.ts; a new immutable release and consumer validation are required before adopting new exports from the registry.

redactFields now reuses @zucker-framework/core/privacy. inspectUserAgent(ua) and UserAgentDetails reuse @zucker-framework/core/user-agent, exposing nullable browser/OS/device details and desktop/mobile/tablet/bot classification. The application chooses labels, missing-value text and version display. These explicit Core entry points contain no Node dependencies; frontend code does not import the Core root.