feat: rename moto → fstack across docs and scripts

[federicodeponte]

Summary

Internal rename to match the GitHub-level rename (moto → fstack) done on 2026-05-05. Repo URL redirect was already working; this PR updates the user-facing strings inside the repo.

What changed

• 53 files: README, install.sh, scripts, systemd unit content, comments, echo strings
• 213 insertions, 200 deletions
• File names and directory layout preserved (no breakage for users with ~/.claude/ already installed)
• systemd unit file names kept as moto-*.{timer,service} (renaming would break installed services); only content updated

What's preserved

• ~/.claude/ install layout
• Internal script function names, variable names, paths
• File/directory names (mac/, server/, etc.)
• Asset filenames

Test plan

• grep -ri "moto" . returns only historical/redirect-context references
• ./install.sh --copy still works on a clean machine
• systemd units installed under old names still load
• README hero image renders