feat(setup): add terminal setup recipe

[yukazakiri]

Summary

Adds a new interactive /setup-terminals recipe that lets users install a terminal emulator and automatically sets it as the iNiR default.

Problem

Currently there is no setup recipe for terminal emulators. Users must manually install their preferred terminal and update config.json to set it as the default for Mod+T / Mod+Return keybinds.

Changes

New file: scripts/setup/terminals.sh

• Interactive menu — choose from 6 terminal emulators:
  • Kitty, Foot, Alacritty, WezTerm, Ghostty, Konsole
• Distro-aware installation:
  • Arch: installs via install_arch (repo + AUR support)
  • Non-Arch: falls back to Flatpak when available
• Auto-configures iNiR defaults — updates config.json:
  • apps.terminal → selected terminal key
  • apps.update → <terminal> -e arch-update
• Safe config editing — uses jq with atomic temp-file + mv
• Symlink-aware — resolves symlink targets before overwriting
• Developer-friendly:
  • Clear section comments
  • Consistent error handling (holds terminal open on failure)
  • Easy to add new terminals (just append to the TERMINALS table)

Design

Follows the existing setup recipe pattern (spotify.sh, editors.sh):

• Metadata header for auto-discovery by _scan.sh
• setup_init / setup_progress / setup_done / setup_finish_pause flow
• Phase-based functions for maintainability

Testing

• bash -n scripts/setup/terminals.sh — syntax clean
• bash scripts/setup/_scan.sh | jq '.[] | select(.slug == "terminals")' — discovered correctly
• Menu renders to stderr, index returned on stdout
• Cancel option exits gracefully with "No changes made"

Related

• Plan: docs/superpowers/plans/2026-05-24-setup-terminals-recipe.md

[yukazakiri]

Updated this PR to simplify distro support:

• Only Arch and Fedora are supported natively (no Debian/openSUSE/Void)
• Arch fallback chain: official repo → AUR → Flatpak → error
• Fedora fallback chain: dnf → Flatpak → error
• All distro-specific logic is self-contained in terminals.sh

This keeps the recipe focused and maintainable.

[snowarch]

Thanks @yukazakiri — clean, additive recipe that follows the existing setup pattern. Queued for an install test before merge.