refactor(setup): restructure installer into setup/ modules

[codepuncher]

What

Restructure the installer for clearer design, behavior-preserving except two latent bug fixes.

• Relocate the installer library out of shell/functions (which lived under shell/ but was only ever sourced by setup.sh) into a new setup/ directory split by concern: common.sh, symlinks.sh, packages-arch.sh, packages-wsl.sh, languages.sh, tools.sh, services.sh.
• Turn setup.sh into a thin orchestrator: sources the modules, owns the y/n prompts and OS dispatch, and adds --help / --reinstall.
• Delete shell/functions.

Bug fixes

• backup() wrote to a hardcoded ${HOME}/.dotfiles/backups/; now uses ${SCRIPT_PATH}/backups/ (worked only when the repo lived at ~/.dotfiles).
• reinstall_dotfiles was documented but never sourced into any shell, so it was uncallable; replaced by ./setup.sh --reinstall.

Notes

• Function bodies moved verbatim. A few minimal, justified # shellcheck disable=... directives were added because shell/functions was never CI-linted but the new .sh files are.
• Docs (README.md, CLAUDE.md) updated to the new layout.

Verification

• shellcheck setup.sh setup/*.sh clean; bash -n on all files passes.
• ./setup.sh --help and unknown-flag handling verified.
• DRY smoke of the Arch dispatch path confirmed routing through the moved modules.

[Copilot]

Pull request overview

This PR restructures the dotfiles installer by moving the previously monolithic shell/functions library into a new setup/ module layout, making setup.sh a thin orchestrator with --help and --reinstall support, while preserving behavior aside from the two stated bug fixes (backup path and reinstall entrypoint).

Changes:

• Split installer logic into setup/*.sh modules (common, symlinks, packages, languages, tools, services) and removed shell/functions.
• Updated setup.sh to source modules, handle CLI flags (--help, --reinstall), and orchestrate interactive flows.
• Updated docs to reflect the new reinstall mechanism (./setup.sh --reinstall).

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
shell/functions	Removed legacy installer function library (replaced by setup/ modules).
setup/common.sh	Common helper functions (section output, OS detection, GitHub release tag lookup, AUR helper logic).
setup/symlinks.sh	Directory initialization + backup + symlink creation logic (now uses ${SCRIPT_PATH}/backups).
setup/packages-arch.sh	Arch package installation and post-install steps.
setup/packages-wsl.sh	WSL/Ubuntu package installation and related setup helpers.
setup/languages.sh	Language/runtime/toolchain installers (nvm/node, rustup, composer, pipx, cargo).
setup/tools.sh	Tool installers (zinit, tmux TPM).
setup/services.sh	Service setup functions (systemd units + MySQL bootstrap).
setup.sh	New orchestrator: sources modules, provides --help/--reinstall, runs interactive flow.
README.md	Docs updated to use ./setup.sh --reinstall instead of a shell function.

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 9 comments.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 6 comments.

[Copilot]

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Copilot reviewed 13 out of 13 changed files in this pull request and generated 5 comments.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 1 comment.