feat: grpc 기능 deep 구현

src/grpc/grpc-proto-contract/build.gradle

@@ -0,0 +1,12 @@
+apply plugin: 'java-library'
+
+// Schema source of truth: the `.proto` files plus the rule engine that judges them.
+//
+// No protobuf plugin and no protoc invocation here — see
+// docs/superpowers/specs/2026-08-30-grpc-platform-adaptation-design.md D6. The validator reads
+// `.proto` text and enforces the Stable style manifest (proto3 + explicit optional, package
+// versioning, reserved history, enum zero suffix, WKT allowlist), which is the invariant the plan
+// owns; running protoc is a separate, gated decision.
+dependencies {
+    api project(':grpc:grpc-core-api')
+}