A 45-year-old man is referred to psychiatry by his general practitioner after a workplace conflict. Colleagues describe him as suspicious, argumentative, and unwilling to delegate tasks. He has held the same job for 15 years but has had multiple conflicts with supervisors, whom he believes are 'out to get him.' He interprets neutral comments as personal insults and has filed three formal complaints against coworkers for perceived slights. He has few friends and avoids social gatherings, believing people are untrustworthy. He denies hearing voices or having delusions, and his cognitive function is intact. What is the most likely personality disorder diagnosis?