common(fix[logs]): use past-tense message for pre-execution log

why: CLAUDE.md logging standards require past-tense event messages.
     "running %s" used present progressive; "tmux command dispatched"
     matches the post-execution "tmux command completed" style.
what:
- Change pre-execution log message from "running %s" to "tmux command dispatched"
- Remove redundant format arg (command already captured in tmux_cmd extra)

Author: tony

src/libtmux/common.py

@@ -263,8 +263,7 @@ def __init__(self, *args: t.Any, tmux_bin: str | None = None) -> None:
         if logger.isEnabledFor(logging.DEBUG):
             cmd_str = shlex.join(cmd)
             logger.debug(
-                "running %s",
-                cmd_str,
+                "tmux command dispatched",
                 extra={"tmux_cmd": cmd_str},
             )