chore(deps): update golang.org/x/crypto and golang.org/x/net; docs cleanup

[mrz1836]

Description of Changes

• Dependency updates:
  • golang.org/x/crypto v0.48.0 → v0.52.0
  • golang.org/x/net v0.51.0 → v0.55.0
• Documentation cleanup in README.md:
  • Replaced the stale "Headers Client" example link with the "SPV Validation" example (docs/examples/validate_spv/).
  • Fixed typo "Compatability" → "Compatibility".
  • Removed the dangling roadmap reference.
  • Corrected the license link from LICENSE.txt to LICENSE.

Linked Issues / Tickets

N/A

Testing Procedure

Dependency-only and documentation changes; no source code modified.

• I have added new unit tests
• All tests pass locally
• I have tested manually in my local environment
• All tests pass when using go test ./...

Checklist:

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have updated CHANGELOG.md with my changes
• I ran golangci-lint run
• I have run go fmt and go vet one final time before requesting a review

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
auth/utils/validate_certificates.go	83.33%	1 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud