Preserve complete TVScraper cast for recording search

[hotzenplotz5]

What changed

• raise the recording metadata people safety bound from 12 to 256
• enlarge the bounded RMETA payload buffer so complete casts, character names, and portrait references can cross SuiteBridge
• add a regression test with a 52-person cast where John Travolta appears beyond the former twelve-person cutoff

Why

TVScraper can return actors in a database-dependent order. VDR-Suite previously truncated that list after twelve entries before persistence, so prominent actors such as John Travolta in Pulp Fiction could disappear from the recording person index even though TVScraper contained them.

The recording metadata handoff defines people as authoritative persistent search data. A UI-sized display limit must therefore not be applied at the provider-to-persistence boundary.

Impact

Recording enrichment can now preserve the provider cast for persistent person search. Frontends may still apply their own presentation limits without losing searchable metadata.

Validation

• reviewed vdr-plugin-suite-bridge/docs/RECORDING-METADATA-HANDOFF.md
• retained a bounded transport contract with 256 people and a 256 KiB payload
• extended test_suitebridge_recording_metadata_contract.cpp to verify John Travolta survives beyond position 12
• retained rejection of more than kMaxPeople and incomplete oversized payload behavior

Full compilation was not executed in this environment; the focused contract test is included for the repository CI/local VDR build.