v1.4.0

- feat(cli): multi-program projects with multi-select picker
- feat(cli): proz <path> adds a project without cd'ing there
- feat(cli): "+ Add project" row in the picker, launch-time program picker
- feat(cli): proz list --json for scripting/agent use, plus
  --filter/--sort/--limit
- feat(cli): installable proz-agent Claude Code plugin/skill
  (marketplace.json + plugin.json, no daemon)
- fix(cli): completion respects explicit shell arg, no longer prints a
  hint on every shell startup
- build: strip debug symbols in release binaries (~30% smaller)
- chore: gofmt entire codebase, technical help/README rewrite