Support read only mode (#36)

Fix: #35
Reviewed-on: https://gitea.com/gitea/gitea-mcp/pulls/36
Co-authored-by: hiifong <f@ilo.nz>
Co-committed-by: hiifong <f@ilo.nz>

operation/repo/branch.go

@@ -10,6 +10,7 @@ import (
 
 	gitea_sdk "code.gitea.io/sdk/gitea"
 	"github.com/mark3labs/mcp-go/mcp"
+	"github.com/mark3labs/mcp-go/server"
 )
 
 const (
@@ -44,6 +45,21 @@ var (
 	)
 )
 
+func init() {
+	Tool.RegisterWrite(server.ServerTool{
+		Tool:    CreateBranchTool,
+		Handler: CreateBranchFn,
+	})
+	Tool.RegisterWrite(server.ServerTool{
+		Tool:    DeleteBranchTool,
+		Handler: DeleteBranchFn,
+	})
+	Tool.RegisterRead(server.ServerTool{
+		Tool:    ListBranchesTool,
+		Handler: ListBranchesFn,
+	})
+}
+
 func CreateBranchFn(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
 	log.Debugf("Called CreateBranchFn")
 	owner, ok := req.Params.Arguments["owner"].(string)