Add pj deepseek command to query account balance and
pj deepseek setkey to store API key in local cache.
Also extract Python launcher into its own module (pj_python.nu)
and add common aliases (g, c, tree, myip, ports, df, reload, edit).
- only clone missing nu_scripts cache when using -u/-f
- keep default pj completion as non-cloning check mode
- align completion flag help text with new behavior
- generate cache registry module from command list and load it at startup
- add pj completion sync (-s) with optional help and restart behavior
- keep missing-cache fallback via noop module and preserve cache ignore rules
- switch completion module imports to export use so externs propagate
- extend managed completion command set and required file checks
- rename prompt static cache env var to PJ_LEFT_PROMPT_STATIC_PART
- load completion module via use in nu_polyjuice
- precompute os symbol, user/host, ssh flag, shell label and newline sequence at startup
- reuse cached values in _pj_left_prompt to reduce per-render overhead
gwbeip