Diagnose project prerequisites without running pipeline steps

Usage: barca doctor [OPTIONS] [FILES]...

Arguments:
  [FILES]...  Python files or directories to inspect (default: discovered project sources)

Options:
      --json       Emit JSON on stdout (the default when stdout is not a terminal)
      --pretty     Emit human-readable output (the default when stdout is a terminal)
      --env <ENV>  Environment name (separates cache/state per environment)
  -h, --help       Print help

Examples:
  barca doctor                      # diagnose the discovered project
  barca doctor pipeline.py --json    # structured checks, no steps executed
  barca doctor src/ --env local --pretty   # selected sources and environment

Checks project root, Python, config, state mode, cache writability, metadata integrity,
static source parsing, and configured stores. Never imports pipeline modules or evaluates
dynamic partition expressions. Prints the report on stdout; exit 0 when all checks pass,
3 when a prerequisite fails. Store probes list but never create buckets or objects.
More: barca docs doctor
