Updated our Employer Guidelines: job scams and unpaid labor

We added two things to our Employer Guidelines (linked from every job submission) that were real gaps, not just wording:

A new "This isn't a real job" section names the concrete signs of a job scam -- being asked for a bank account, routing number, ID copy, or any payment before you're hired, or an "interview" that's entirely over chat with someone who won't get on a call -- and points directly at the "Job scam" option already on every listing's Report button.

Our existing spec-work policy is now explicitly a broader unpaid-labor policy too: an unpaid "trial week" doing real production work, "equity only" standing in for real pay, and unpaid "training" that's actually the job are all called out by name now, not just speculative client work.