With Standing in the Breach, Jackson Browne makes a stunningly bold statement of purpose in a moment that might have been more reflective. After all, his very best music was the subject of a celebrated recent tribute album, something that might have left a lesser artist more humbled than ambitious. Not Browne. His first album of new songs since 2008, set for release on Browne’s own Inside Recordings in October, finds him working at peak creativity — as a writer, as a performer, as a bandmate.