v0.5.1 — Setup path warning + CI hardening

Fixed

• mpg setup --project-dir /nonexistent now emits a stderr warning ("directory does not exist and will be created") before proceeding. No warning when --mcp-only is used or when the directory exists. --dry-run also warns (typo detection). (closes #96)
• check-python-release.yml: curl now uses -f (fail on HTTP errors), --retry 2, --connect-timeout 10, --max-time 30. jq uses capture()? (try operator for non-matching release names) and last // empty (prevents "null" string on empty array). Pipeline errors are caught by if ! wrapper instead of relying on set -e with bare assignment. (closes #97)

Added

• 4 new tests (1032 total).