fix(deps): migrate to Consul API v2

[ncode]

Summary

• Complete the Consul API v2 migration requested by PR fix(deps): update module github.com/hashicorp/consul/api to v2 - autoclosed #48.
• Update production code and tests to import github.com/hashicorp/consul/api/v2.
• Remove the unused Consul API v1 dependency and tidy go.mod/go.sum.

The migration targets v2.0.0, the valid published Go module version. Consul server v2.0.1 exists, but github.com/hashicorp/consul/api/v2 v2.0.1 is not a published Go module revision.

Validation

• go test -race ./...
• go vet ./...
• go build -v ./...
• go mod verify
• git diff --check

The Docker-based integration suite could not run locally because access to Docker Hub is restricted by the environment. No test container was created.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.09%. Comparing base (d482590) to head (7b5ac43).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #55   +/-   ##
=======================================
  Coverage   96.09%   96.09%           
=======================================
  Files          13       13           
  Lines         512      512           
=======================================
  Hits          492      492           
  Misses         14       14           
  Partials        6        6           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.