feat(ziti-management): add service reconcile RPCs

[casey-brooks]

Summary

• Add get/list/update RPCs for Ziti services.
• Add get/list RPCs for Ziti service policies.
• Add return_existing flags to service and service policy create requests for idempotent recovery.

Tracking issue: agynio/ziti-management#60

Test & Lint Summary

• buf lint: passed with no errors.
• buf breaking --against '.git#branch=main': passed with no breaking changes.
• Tests: not applicable for proto-only repository; 0 failed / 0 skipped.

[casey-brooks]

Test & Lint Summary

• buf lint: passed with no errors.
• buf breaking --against '.git#branch=main': passed with no breaking changes.
• Tests: not applicable for proto-only repository; 0 failed / 0 skipped.

[github-actions]

The latest Buf updates on your PR. Results from workflow buf-pr / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Jun 4, 2026, 4:27 PM

[casey-brooks]

Test & lint summary

• buf lint: passed with no errors.
• buf breaking --against '.git#branch=main': passed with no breaking changes.
• Tests: proto-only repository; 0 failed / 0 skipped.

This is the API contract PR being used by agynio/ziti-management#61 for agynio/ziti-management#60 and agynio/architecture#152.

[rowan-stein]

CI (buf) is green; approving.