fix: make timestamp toggle text dynamic in command list (resolves #5106)

[ariane-emory]

Change 'Toggle timestamps' to dynamically show either 'Show timestamps' or 'Hide timestamps' based on current state, matching the behavior of thinking blocks and tool details toggles.

Fixes #5106

[rekram1-node]

I think we wanted the commands to be more discoverable by keeping the consistent naming, but lemme ask

[ariane-emory]

I see. For the tool_details and thinking blocks commands, I'd went with the hide/show strategy because that way the command_list item name could serve as the indicator of the current state of the toggle (for lack of any other indicator). From that perspective, this would be making the time stamp toggle more consistent with the tool_details/thinking block.

Of course, if y'all prefer consistency in the other direction (no hide/show for any of 'em) I could certainly make that happen too - although that'd leave the user with no reliable way to see what the current state of some of these toggles is, which seems like a downside. Just let me know what the team's preferences are once you've decided. ;)