Write a concise, fact-checked timeline of the Everett shooting, starting with the 12:50 p.m. call and tracing the arrest, while clearly labeling confirmed facts versus ongoing investigations. Include a brief background portrait of the delivery driver suspect, noting what is known and what remains unverified, and balance this with contextual information about their employer and route. Add a sidebar on safety measures and union responses, outlining implemented or proposed protections for mail carriers. Highlight how public safety communications were handled by the postal service and local police, and cite at least two credible sources for each major claim. End with a takeaway on lessons for worker safety and policy implications.