feat: Add gRPC API Layer - Phase 6 Integration

Added Protobuf definitions and gRPC services for all CQ layers:

Protobuf Files (4):
- configuration.proto: 2 Commands + 3 Queries (5 RPCs)
- clubmembership.proto: 3 Commands + 3 Queries (6 RPCs)
- networkmembership.proto: 3 Commands + 3 Queries (6 RPCs)
- commission.proto: 5 Commands + 4 Queries (9 RPCs)

gRPC Services (4):
- ConfigurationService: SetConfigurationValue, Deactivate, GetByKey, GetAll, GetHistory
- ClubMembershipService: Activate, Deactivate, AssignFeature, Get, GetAll, GetHistory
- NetworkMembershipService: Join, Move, Remove, GetPosition, GetTree, GetHistory
- CommissionService: Calculate+Process+Withdraw (5 commands), Get queries (4)

Features:
- HTTP transcoding enabled via google.api.http annotations
- Auto-registration via ConfigureGrpcEndpoints
- MetaData pagination support
- Request/Response DTOs for all endpoints
- Integration with MediatR CQRS handlers

Total: 4 proto files, 4 service classes, 26 RPC endpoints
Build: ✅ Successful (0 errors)

src/CMSMicroservice.Protobuf/Protos/clubmembership.proto

@@ -0,0 +1,166 @@
+syntax = "proto3";
+
+package clubmembership;
+
+import "public_messages.proto";
+import "google/protobuf/empty.proto";
+import "google/protobuf/wrappers.proto";
+import "google/protobuf/timestamp.proto";
+import "google/api/annotations.proto";
+
+option csharp_namespace = "CMSMicroservice.Protobuf.Protos.ClubMembership";
+
+service ClubMembershipContract
+{
+    rpc ActivateClubMembership(ActivateClubMembershipRequest) returns (google.protobuf.Empty){
+        option (google.api.http) = {
+            post: "/ClubMembership/Activate"
+            body: "*"
+        };
+    };
+    rpc DeactivateClubMembership(DeactivateClubMembershipRequest) returns (google.protobuf.Empty){
+        option (google.api.http) = {
+            post: "/ClubMembership/Deactivate"
+            body: "*"
+        };
+    };
+    rpc AssignFeatureToMembership(AssignFeatureToMembershipRequest) returns (google.protobuf.Empty){
+        option (google.api.http) = {
+            post: "/ClubMembership/AssignFeature"
+            body: "*"
+        };
+    };
+    rpc GetClubMembership(GetClubMembershipRequest) returns (GetClubMembershipResponse){
+        option (google.api.http) = {
+            get: "/ClubMembership/Get"
+        };
+    };
+    rpc GetAllClubMemberships(GetAllClubMembershipsRequest) returns (GetAllClubMembershipsResponse){
+        option (google.api.http) = {
+            get: "/ClubMembership/GetAll"
+        };
+    };
+    rpc GetClubMembershipHistory(GetClubMembershipHistoryRequest) returns (GetClubMembershipHistoryResponse){
+        option (google.api.http) = {
+            get: "/ClubMembership/GetHistory"
+        };
+    };
+}
+
+// Activate Command
+message ActivateClubMembershipRequest
+{
+    int64 user_id = 1;
+    int64 package_id = 2;
+    google.protobuf.StringValue activation_code = 3;
+    int32 duration_months = 4;
+}
+
+// Deactivate Command
+message DeactivateClubMembershipRequest
+{
+    int64 user_id = 1;
+    string reason = 2;
+}
+
+// AssignFeature Command
+message AssignFeatureToMembershipRequest
+{
+    int64 user_id = 1;
+    int64 product_id = 2;
+    google.protobuf.Int32Value quantity = 3;
+    google.protobuf.Int32Value duration_days = 4;
+}
+
+// Get Query
+message GetClubMembershipRequest
+{
+    int64 user_id = 1;
+}
+
+message GetClubMembershipResponse
+{
+    int64 id = 1;
+    int64 user_id = 2;
+    int64 package_id = 3;
+    string package_name = 4;
+    string activation_code = 5;
+    google.protobuf.Timestamp activated_at = 6;
+    google.protobuf.Timestamp expires_at = 7;
+    bool is_active = 8;
+    google.protobuf.Timestamp created = 9;
+    repeated MembershipFeatureModel features = 10;
+}
+
+message MembershipFeatureModel
+{
+    int64 product_id = 1;
+    string product_name = 2;
+    int32 quantity = 3;
+    google.protobuf.Timestamp expires_at = 4;
+    bool is_active = 5;
+}
+
+// GetAll Query
+message GetAllClubMembershipsRequest
+{
+    google.protobuf.Int64Value user_id = 1;
+    google.protobuf.Int64Value package_id = 2;
+    google.protobuf.BoolValue is_active = 3;
+    google.protobuf.BoolValue is_expired = 4;
+    int32 page_index = 5;
+    int32 page_size = 6;
+}
+
+message GetAllClubMembershipsResponse
+{
+    messages.MetaData meta_data = 1;
+    repeated ClubMembershipModel models = 2;
+}
+
+message ClubMembershipModel
+{
+    int64 id = 1;
+    int64 user_id = 2;
+    string user_name = 3;
+    int64 package_id = 4;
+    string package_name = 5;
+    string activation_code = 6;
+    google.protobuf.Timestamp activated_at = 7;
+    google.protobuf.Timestamp expires_at = 8;
+    bool is_active = 9;
+    bool is_expired = 10;
+    google.protobuf.Timestamp created = 11;
+}
+
+// GetHistory Query
+message GetClubMembershipHistoryRequest
+{
+    google.protobuf.Int64Value user_id = 1;
+    google.protobuf.Int64Value package_id = 2;
+    int32 page_index = 3;
+    int32 page_size = 4;
+}
+
+message GetClubMembershipHistoryResponse
+{
+    messages.MetaData meta_data = 1;
+    repeated ClubMembershipHistoryModel models = 2;
+}
+
+message ClubMembershipHistoryModel
+{
+    int64 id = 1;
+    int64 club_membership_id = 2;
+    int64 user_id = 3;
+    google.protobuf.Int64Value old_package_id = 4;
+    google.protobuf.Int64Value new_package_id = 5;
+    google.protobuf.Timestamp old_activated_at = 6;
+    google.protobuf.Timestamp new_activated_at = 7;
+    google.protobuf.Timestamp old_expires_at = 8;
+    google.protobuf.Timestamp new_expires_at = 9;
+    int32 action = 10; // ClubMembershipAction enum
+    string performed_by = 11;
+    string reason = 12;
+    google.protobuf.Timestamp created = 13;
+}