Fix copy-paste error messages in log strings

1. agent.py: f-string had literal 'f' before variable, producing
   "Find the current log file here: f/Users/..." instead of the path.

2. ls.py: delete_text_between_positions logged "insert_text_at_position
   called before Language Server started" — wrong method name.

src/serena/agent.py

@@ -483,7 +483,7 @@ class SerenaAgent:
         else:
             log_path = SerenaPaths().last_returned_log_file_path
             if log_path is not None:
-                return f"Find the current log file here: f{log_path}"
+                return f"Find the current log file here: {log_path}"
             else:
                 return "Unfortunately, logs are not available. We recommend enabling the web dashboard/logging in general."
 

src/solidlsp/ls.py

@@ -817,7 +817,7 @@ class SolidLanguageServer(ABC):
         Delete text between the given start and end positions in the given file and return the deleted text.
         """
         if not self.server_started:
-            log.error("insert_text_at_position called before Language Server started")
+            log.error("delete_text_between_positions called before Language Server started")
             raise SolidLSPException("Language Server not started")
 
         absolute_file_path = str(PurePath(self.repository_root_path, relative_file_path))