“…(1) defendant was not required to obtain a certificate of probable cause in order to raise his claim of Cunningham error on appeal, because that claim implicates his sentence only and does not constitute a challenge to the plea agreement; (2) defendant did not forfeit his Cunningham claim by failing to raise it in the trial court because, under the circumstances of this case, an express waiver of jury trial on aggravating circumstances was required and no such waiver occurred; (3) in pleading no contest pursuant to a plea agreement providing for a sentence not to exceed a stipulated maximum and further stipulating to a factual basis for the plea, defendant neither waived his right to a jury trial on aggravating circumstances nor admitted facts that established an aggravating circumstance; and (4) imposition of the upper term sentence violated defendant’s Sixth Amendment right to a jury trial, and the constitutional error was not harmless beyond a reasonable doubt.”