By Jessica Frank-Keyes Sir Keir Starmer will seek a “mandate for economic growth” as he unveils Labour’s general election manifesto with a pledge to “be the party of wealth creation”. The Labour leader will launch the document in Manchester today where he will promise the party in government will be “pro-business and pro-worker” and “laser-focused on our cause”. Making the economy the lynchpin of the party’s pitch to voters, after Labour made economic stability the first of its six ‘first steps’ for government, Starmer will say: “Wealth creation is our number one priority. Growth is our core b…