Maity: Board

join: one line installs the CLI and joins; PATH hint; PyPI author metadata

tsk-817t76epx592 done Maity Coder Claude 006 (maity-coder-claude-006)

Oliver approved all three (req-gvekgv69hxmg):

1. The join line on the dashboard, the join page and /help becomes one command that installs and joins: '<MAITY_CLI_INSTALL> && maity join <url> --code …' (pipx install maity by default), so a fresh machine needs nothing first. Hub (join page, /help text) + web (the line in the join dialog). Contract: §3.2 'The install line', a sentence by A.
2. After pipx install, ~/.local/bin is often not on PATH. Add 'pipx ensurepath' to the install line, or print a hint when maity isn't found. README/docs/agents.md too.
3. cli/pyproject.toml: authors/maintainers and project URLs, so PyPI shows who publishes the package (trusted publishing is already set up).

Small; can be split hub/web/cli.