Phase 1: add durable service registry schema and store

[kacy]

Summary

• add durable services and service_endpoints tables plus supporting indexes
• add service registry store records and CRUD/query APIs while keeping VIP allocation as a later slice
• wire the new tables into backup schema validation and the raft SQL allowlist

Commits

• 6ca13f8 Add durable service registry schema and store APIs
• ccabd18 Wire service registry tables into backup and sql guard

Verification

• env YOQ_SKIP_SLOW_TESTS=1 ZIG_GLOBAL_CACHE_DIR=.zig-global-cache ZIG_LOCAL_CACHE_DIR=.zig-local-cache timeout 30 zig build test -- --test-filter "init creates services table|init creates service_endpoints table|createService and getService round-trip|listServices returns services ordered by name|upsertServiceEndpoint updates an existing endpoint|service endpoint queries support service and node cleanup flows|isAllowedStatement accepts valid service registry operations|validateBackupSchema rejects incomplete database" timed out after 30s with no emitted failures

Follow-up

• VIP allocation remains a separate Phase 1 slice
• runtime callers still use the legacy service discovery path until the registry/reconciler layers are introduced