Fastly ClientInfo #90

Description

Complete Fastly population of the portable ClientInfo contract. Fastly request conversion already reads get_client_ip_addr() into Fastly request context; geolocation and TLS facts are not mapped into a shared metadata API. The raw request-extension hook is a useful seam, but requires application-owned types and does not itself implement ClientInfo.

Steps to reproduce

1. Inspect FastlyRequestContext and convert_request.
2. Identify the captured fields and their handler access path.
3. Look for built-in portable geolocation and TLS metadata population.

Expected behavior

Fastly handlers receive available client IP/geolocation/TLS facts through the shared metadata contract.

Impact

Only client IP has built-in adapter metadata; richer facts require custom Fastly integration.

Proposed fix

Map Fastly request client APIs into the shared contract from #89, preserving runtime availability and provenance. Reuse the existing conversion seam and keep the separate JA4 acceptance in #283 explicit.

Done when

• Existing client-IP access is preserved through the shared API.
• Available geolocation/TLS values are captured and unavailable values remain absent.
• Fastly runtime contract tests cover populated and missing metadata.

Related

Parent #88; story #89; fingerprint follow-up #283. Merged PR #306 supplies an application-defined raw request hook, not a standard ClientInfo implementation.