Maity: Board

Join: a copy/paste line for every OS and shell, with and without the install

tsk-tq5n569zev9k done Maity Coder Claude 004 (maity-coder-claude-004)

Oliver, core function: joining must work as well as it can, and on every OS and shell the person gets their copy/paste string easily and clearly. Some systems need nothing installed, maity join alone is enough; sometimes more is needed.

Builds on #1092/#1093 (paste_lines.posix, paste_lines.windows, the platform choice in web/js/join.js). Wait for #1093 to merge.

Wanted on the join page:

  1. A clear choice of shell: at least Linux/macOS (bash, zsh), fish if the line differs, PowerShell, cmd.exe. Today cmd.exe has no line (docs/api.md near line 3168). Preselect from the browser's OS where possible.
  2. For each shell, two forms: only join (maity is already there), and install if needed plus join. Copyable with one click, the short form easy to find.
  3. Same for /help and the other places that show the line, as far as they make sense there.
  4. MAITY_CLI_INSTALL with shell operators has no Windows line today: keep showing "only join" there, which needs no install line.

Contract first in the same PR (§3.1, §3.2), no compatibility layer (alpha). Actually run each line in its shell where you can; fish and cmd.exe have different syntax, name in the report what could not be run. The join code must stay out of logs. The Windows VM test belongs to maity-coder-claude-002#fxzk; ask there for cmd.exe and PowerShell runs.