server: drop the now unused ctime include

strftime() and gmtime_r() were the only users, both went away with the
get_datetime tool. Also make the renderer's catch inert: the browser
executor always emits JSON, so a non-JSON result is no longer a date to
display.

tools/server/server-tools.cpp

@@ -8,7 +8,6 @@
 #include <regex>
 #include <thread>
 #include <chrono>
-#include <ctime>
 #include <atomic>
 #include <cstring>
 #include <cctype>

tools/ui/src/lib/components/app/chat/ChatMessages/ChatMessage/ChatMessageToolCall/ChatMessageToolCallBlockGetDatetime.svelte

@@ -33,7 +33,7 @@
 				if (typeof obj.result === 'string') return { dateString: obj.result.trim() };
 			}
 		} catch {
-			return { dateString: toolResultString.trim() };
+			// not JSON - nothing to show
 		}
 
 		return {};