Quote "$@" throughout the shift script (#1081)

[dduugg]

Fixes #1081.

Every ./shift subcommand that forwards arguments used an unquoted $@, at each hop of the call chain (dispatcher -> sub_* -> sub_compose -> docker). shift is a bash script, and unquoted $@ in bash re-splits each argument on whitespace and then glob-expands the results.

The most visible casualty is ./shift mysql -e "<sql>", which never runs the SQL and instead prints mysql's usage text, because the SQL string is split into many arguments before mysql sees it.

The change

Quote "$@" at all 18 forwarding sites (the dispatcher, sub_compose, and every sub_* that passes arguments through). The space-free service names that the other subcommands take (./shift logs node, ./shift down) are unaffected.

Scope is limited to the $@ word-splitting bug. The ${MYSQL_USER} / ${MYSQL_DATABASE} values on the mysql lines are controlled and space-free, so they are left as-is to keep the diff focused.

Verification

Driving the actual script with a stubbed docker on PATH, so the arguments that would reach docker compose can be counted. Argument used: -e "SELECT * FROM calevent WHERE title = 'a b';" (a glob and a space, the two failure modes):

fixed (this branch):    docker received 14 args
  ...
  [12] -e
  [13] SELECT * FROM calevent WHERE title = 'a b';        <- one intact argument

old (upstream/main):    docker received 42 args
  ...
  [13] SELECT
  [14] app                                                <- the * expanded to the repo listing
  [15] backend
  ... ( every file in the repo ) ...
  [40] 'a                                                 <- the space split the value
  [41] b';

Ordinary subcommands still pass their arguments correctly (./shift logs node -> compose logs --tail=50 -f node; ./shift down -> compose down), and the unknown-subcommand error path (exit 127) still fires. bash -n shift parses clean.

This bug also bit the verification steps originally written into #1077; the workaround there was to pipe SQL via ./shift mysql-pipe (stdin) instead of passing it as an argument.