node: add config validation command

[malsomesh9]

Summary

• add a peer validate-config command that loads and validates the FSC node configuration before startup
• fail with a clear error when the config is missing fsc.id
• return the concrete config file path via ConfigFileUsed() so the validator can report exactly what it checked

Why

Today, configuration mistakes are often only discovered later during node startup. This adds a lightweight validation tool that helps contributors and operators catch obvious config issues earlier and see which core.yaml was actually loaded.

Testing

• go test ./node/validate
• go test ./platform/view/services/config
• go test ./node/...

Refs #209
Refs #798

[coveralls]

Coverage Report for CI Build 24955777958

Warning

Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes.
Quick fix: rebase this PR. Learn more →

Coverage increased (+0.05%) to 66.915%

Details

• Coverage increased (+0.05%) from the base build.
• Patch coverage: 6 uncovered changes across 1 file (27 of 33 lines covered, 81.82%).
• 9 coverage regressions across 5 files.

Uncovered Changes

File	Changed	Covered	%
node/validate/validate.go	31	25	80.65%

Coverage Regressions

9 previously-covered lines in 5 files lost coverage.

File	Lines Losing Coverage	Coverage
platform/view/services/comm/p2p.go	3	90.24%
platform/view/services/comm/service.go	2	69.07%
platform/view/services/comm/host/websocket/ws/multiplexed_provider.go	2	85.06%
platform/fabric/core/generic/msp/x509/ecdsa.go	1	82.71%
platform/view/services/comm/session.go	1	87.7%

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Coverage Stats

Relevant Lines:	39683
Covered Lines:	26554
Line Coverage:	66.92%
Coverage Strength:	2953.48 hits per line

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💛 - Coveralls

[malsomesh9]

@SaidAltury-ibm @mbrandenburger Plz take a look at this.