SAN FRANCISCO -- Democrat John F. Kerry yesterday countered Republican attempts to label him a pessimist about the US economy, arguing that criticism of the Bush administration's record of job creation actually reflected optimism that the economy could do better. The Massachusetts senator also challenged the fiscal record of the GOP's favorite optimist, Ronald Reagan -- Kerry's first broadside against the former president since his death June 5. Kerry, who is in California for a two-day campaign swing that the Bush reelection camp has dubbed ''the pessimism and misery tour," also launched a new line of attack against Washington Republicans,...