Document Token SDK Monitoring Metrics and Identify Missing Metrics

[AkramBitar]

1. List and document all monitoring information (metrics) collected by the Token SDK.
2. Review the list and identify any missing monitoring metrics that should be added.

[SuyashAlphaC]

hey @AkramBitar can you pls assign this issue to me🙏

[adecaro]

go ahead @SuyashAlphaC . Thanks for volunteering 🙏

[SuyashAlphaC]

Hey @AkramBitar @adecaro, I've opened a PR for this 🙏
I have went through the whole tree and documented all the metrics the SDK emits (50 of them) in a new docs/metrics.md — driver services, ttx lifecycle, finality, envelope sessions, auditor, selection, certification, identity caches, fabric-x queue. each with type/labels/what it measures, linked from the monitoring doc.

also added a ranked "gaps" section for the stuff that's not instrumented yet — biggest one is the storage layer (no metrics at all), then the auditor lock manager, the standard fabric network/approval path, validation/double-spend, a tx-level failure counter, and wallet lookups. put concrete metric suggestions for each so they're easy to pick up later.

PR: #1749