feat(server): commit intrinsic event message text

[jscott3201]

Summary

• select deterministic intrinsic event message text from object identity and the committed state transition
• store the exact selected text in the matching transition-history coordinate before distribution
• emit the committed snapshot unchanged to confirmed and unconfirmed recipients, including retries
• cover all nine built-in intrinsic object families and preserve local history commits when distribution is suppressed

Scope

This is the message-text slice only. Event Enrollment message text, configurable message templates, public policy callbacks, Python surfaces, and structured event values remain unchanged or deferred.

Validation

• focused message-policy, history, wire, retry, and Event Enrollment regressions
• cargo test -p bacnet-server --locked
• cargo fmt --all -- --check
• workspace Clippy and default/feature test matrices
• root crate check
• generated-document, file-size, secret, and diff checks

Refs #135