fix: preserve argv boundaries in spin run and spin exec

[yusufkandemir]

Problem

spin run and spin exec lose argument boundaries when any argument contains a space or quoted string. Minimal reproduction:

spin run --quiet php php -r 'echo "hi";'
# [19-May-2026 20:00:00 UTC] PHP Parse error:  syntax error, unexpected end of file in Command line code on line 1

The single-quoted PHP source arrives at the container split into two tokens (echo and "hi";), so PHP only sees echo. Same problem causes any spin run php php artisan tinker --execute '...' to fail with similar errors as well. This is especially a big deal with AI agents since Tinker and PHP REPL are important to quickly test/verify certain things.

Cause

spin/lib/actions/run.sh

Line 5 in e205e41

local args=($(filter_out_spin_arguments "$@"))

filter_out_spin_arguments returned its result via echo "${filtered[@]}" (space-joined, unquoted), and the caller word-split that back on IFS. Every argument containing whitespace is gone before reaching docker compose run.

lib/actions/exec.sh had a smaller variant of the same problem: bare $@ instead of "$@".

Fix

Use a global-array return-based solution. The same pattern is also used by the existing prepare_ansible_run.

• filter_out_spin_arguments now writes to SPIN_FILTERED_ARGS
• run.sh copies it into a local array to make the usage easier, preserving the previous DX
• exec.sh quotes "$@".

Bash 3.2 compatibility is required as noted in AGENTS.md(I'd recommend creating a contributing.md or similar, or putting the same requirement elsewhere too). So, I didn't use the nameref(local -n) approach, which would've helped avoid introducing global variables, but it only works in Bash 4.3+.