Feature: Enhance Observable Callback Coverage

[LK-Simon]

Summary

Enhance ESPressio Serial integration so observable lifecycle information from Command, Security, Sockets and related subsystems can be surfaced consistently through diagnostics/monitoring without duplicating primary execution or transport callbacks.

Scope

• Integrate newly observable upstream lifecycle information where Serial diagnostics/monitoring is the natural presentation layer.
• Preserve existing console, logging, command execution and event-monitoring behavior.
• Prefer observing the originating library instead of inventing parallel Serial-specific lifecycle semantics.
• Add optional Event-backed monitoring where appropriate without making ESPressio Event mandatory for core Serial use.
• Add representative tests/examples/documentation for the enhanced monitoring integration.
• Update release metadata, upstream dependency versions, dependency documentation and changelog.

Compatibility

Existing Serial APIs and non-Event use must remain supported.