feat(fxconfig): add basic snapshot validation helper and tests

[sachin9058]

Type of change

• New feature
• Test update

Description

This PR introduces a minimal validation helper for snapshot-like data structures to ensure basic structural correctness before processing.

The validation checks:

• non-empty channel
• presence of namespaces
• non-empty namespace names
• non-empty key sets
• valid (non-empty) keys

The goal is to provide a lightweight guard against malformed snapshot input, helping prevent issues during transformation or export stages.

Unit tests are included to cover both valid and invalid scenarios.

Additional details (Optional)

• Implemented as a standalone utility under internal/validation to keep the scope minimal
• No changes to existing logic or public APIs
• Tests include success and edge-case validation (empty channel, namespaces, keys, etc.)

Validation:

• go test ./tools/fxconfig/... -count=1 passed
• make lint passed

Related issues

Closes #227

[sachin9058]

Hi @cendhu @mbrandenburger,

I’ve opened this PR to add a minimal snapshot validation helper with unit tests.

The goal is to introduce a lightweight validation step for snapshot-like data structures without affecting existing logic.

Would really appreciate your feedback whenever you get a chance. Happy to refine this further based on your suggestions.

Thanks!