fix(gpu): truncate CMD column to 80 chars in pretty/human table output

chore: delete issues/ directory, update docs for GitHub Issues

fix(issue): error paths now exit 1 instead of 0, restore returncode assertions in tests

test(issue): rewrite issue tests to mock GitHub API

feat(issue): rewrite cmd_issue to create GitHub Issues via API

feat(issue): add _get_github_token() helper with tests

docs: rewrite Setup section for new users, make install.sh fault-tolerant

fix(gpu): use ps args= instead of comm= to show full command line

feat(gpu): add --human flag with visual VRAM dashboard

docs: add procyon-gpu skill, update master skill routing

fix(gpu): wrap query_gpu_processes in FileNotFoundError handler, add nonzero exit test

test(gpu): add pretty output and empty process list integration tests

fix(gpu): handle no GPUs detected case per spec

feat(gpu): add procyon gpu subcommand with JSON/pretty output, user filter, and registry status

feat(gpu): add format_gpu_pretty() for human-readable GPU output