Support persistent Close conversation mode

[RANGROO]

Summary

• adds CLOSE as a first-class server execution mode and keeps Close conversations private to the player and resolved responder
• consumes CHIM's authoritative managed audience and separate present_actors snapshot
• adds physically present actors to scene context and event-history membership without making inactive actors responders
• allows compatible gameplay actions to target inactive present actors
• formats present actors as Name [RefID: XXXXXXXX] and asks action schemas to prefer that exact identifier
• preserves explicit actor RefIDs through action post-filtering while retaining actor-name fallback
• keeps rechat generation server-side and blocks automatic rechat while Close mode is active
• handles Close wording, subtitles, memory extraction, Oghma context, and private delivery without changing global distance settings

Compatibility

• no database migration is required
• existing actor-name action targets remain valid
• RefIDs are request-local; persisted event people and audience identity remain name-based
• a supplied RefID is validated by the CHIM plugin before use, then falls back to the supplied actor name
• physical presence does not activate an NPC or widen the managed response audience
• pairs with Dwemer-Dynamics/CHIM#85

Validation

• php -l passed for every changed PHP and test file
• focused presence and RefID tests: 5 tests, 15 assertions passed
• existing Close/asterisk parsing tests passed earlier on this branch
• git diff --check passed
• the broader suite retains unrelated local-environment errors from unavailable PostgreSQL setup, missing ZipArchive, and Windows test-command assumptions

Review notes

• no generated files, database contents, logs, or runtime configuration are included
• the unstable guard requires this PR because core runtime files overlap active development
• the latest RefID/action-target delta is automated-test validated but has not been deployed or verified in-game

Related PR

• Dwemer-Dynamics/CHIM#85