fix(ralph-loop): address hook scripts via CURSOR_PLUGIN_ROOT

[deanrie]

Summary

ralph-loop/hooks/hooks.json still addresses its scripts as ./hooks/capture-response.sh and ./hooks/stop-hook.sh. Plugin hooks do not run from the plugin directory, so from any other cwd those commands fail with exit 127 and the hook never runs. #315 fixed the same layout in advisor a month ago and noted that the plugin registry classifies it as public-invalid; ralph-loop kept the old form, which may be why /add-plugin ralph-loop has nothing to install (#50). This switches both commands to bash "${CURSOR_PLUGIN_ROOT}/hooks/<script>.sh", the form advisor uses.

While here, continual-learning/hooks/hooks.json already uses ${CURSOR_PLUGIN_ROOT} but unquoted; quoted it so a plugin path with spaces keeps working.

loop_limit: null on the stop hook is left as is: the docs define null as "no limit", and ralph-loop enforces its own max_iterations.

No version bump here: #499 already bumps ralph-loop to 1.0.1 and touches the scripts; this PR only changes hooks.json, so the two merge in either order.

Verification

• node scripts/validate-plugins.mjs: All plugins validated successfully.
• Ran both new command strings from /tmp with CURSOR_PLUGIN_ROOT=<repo>/ralph-loop and CURSOR_PROJECT_DIR pointing at an empty directory: both exit 0 with no output (no active loop). The old ./hooks/stop-hook.sh form from the same cwd: no such file or directory, exit 127.
• git diff --check clean.

Refs #50.