feat(grpc): enhance grades and exams data structures

Update the gRPC service definitions and handlers to provide more detailed
information for grades and exams.

- Add `GpaSummary` message to include average GPA, rank, and other
  academic statistics.
- Expand `Grade` message with additional fields like `term`, `nature`,
  `category`, and `is_exam`.
- Refactor `Exam` message to use `week` and `weekday` instead of `room`
  and `seat`.
- Update `TaskHandler.getGrades` to populate the new `GpaSummary` and
  enriched grade details.
- Update protobuf generated files to reflect schema changes.

proto/runner/runner_grpc.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go-grpc. DO NOT EDIT.
 // versions:
-// - protoc-gen-go-grpc v1.5.1
-// - protoc             v3.19.4
+// - protoc-gen-go-grpc v1.6.1
+// - protoc             v7.34.1
 // source: proto/runner/runner.proto
 
 package runner
@@ -76,7 +76,7 @@ type RunnerHubServer interface {
 type UnimplementedRunnerHubServer struct{}
 
 func (UnimplementedRunnerHubServer) Connect(grpc.BidiStreamingServer[StreamMessage, StreamMessage]) error {
-	return status.Errorf(codes.Unimplemented, "method Connect not implemented")
+	return status.Error(codes.Unimplemented, "method Connect not implemented")
 }
 func (UnimplementedRunnerHubServer) mustEmbedUnimplementedRunnerHubServer() {}
 func (UnimplementedRunnerHubServer) testEmbeddedByValue()                   {}
@@ -89,7 +89,7 @@ type UnsafeRunnerHubServer interface {
 }
 
 func RegisterRunnerHubServer(s grpc.ServiceRegistrar, srv RunnerHubServer) {
-	// If the following call pancis, it indicates UnimplementedRunnerHubServer was
+	// If the following call panics, it indicates UnimplementedRunnerHubServer was
 	// embedded by pointer and is nil.  This will cause panics if an
 	// unimplemented method is ever invoked, so we test this at initialization
 	// time to prevent it from happening at runtime later due to I/O.