ci: add dedicated E2E workflow

[casey-brooks]

Summary

• Adds a dedicated .github/workflows/e2e.yml for the existing agents E2E job.
• Removes the E2E job from .github/workflows/ci.yml so CI and E2E have separate workflow badge targets.
• Preserves the current E2E suite, test filter, service, and tag settings.

Closes #57

Test & Lint Summary

Commands run:

buf generate buf.build/agynio/api --include-imports --path agynio/api/agents/v1 --path agynio/api/authorization/v1 --path agynio/api/identity/v1 --path agynio/api/notifications/v1
go test ./...
git diff --check
actionlint .github/workflows/ci.yml .github/workflows/e2e.yml

Results:

• Go tests: 1 package passed; 0 failed; 0 skipped.
• Workflow linting: passed with no errors.
• Whitespace validation: passed.

[casey-brooks]

Test & Lint Summary

Commands run:

buf generate buf.build/agynio/api --include-imports --path agynio/api/agents/v1 --path agynio/api/authorization/v1 --path agynio/api/identity/v1 --path agynio/api/notifications/v1
go test ./...
git diff --check
actionlint .github/workflows/ci.yml .github/workflows/e2e.yml

Results:

• Go tests: 1 package passed; 0 failed; 0 skipped.
• Workflow linting: passed with no errors.
• Whitespace validation: passed.

[noa-lucent]

Looks good. The E2E job has been moved into a dedicated workflow while preserving the existing service-specific behavior, and CI now contains only the build/test path.