feat: add NixOS support, Go, and Ruby on Rails; remove Rust

- Add nixos/ directory with declarative flake.nix and home.nix for NixOS
- Make all setup scripts NixOS-aware with proper detection and early exit
- Update bashrc, zshrc, and aliases with Go, Ruby on Rails, and Nix profile paths
- Replace Rust/Cargo references in shell configs with rbenv/Ruby on Rails
- Update README with NixOS quick start and full documentation

scripts/02-dev-tools-setup.sh

@@ -2,9 +2,43 @@
 
 # 02-dev-tools-setup.sh
 # Installs various development tools and utilities.
+# Supports NixOS (declarative via flake), Fedora, and Debian/Ubuntu.
+# Relies on DISTRO and PACKAGE_MANAGER being set by the caller.
 
 echo "--- Starting Development Tools Setup ---"
 
+if [ -z "$DISTRO" ] || [ -z "$PACKAGE_MANAGER" ]; then
+    echo "ERROR: DISTRO and PACKAGE_MANAGER must be set in the environment."
+    exit 1
+fi
+
+# ── NixOS path ─────────────────────────────────────────────
+if [ "$DISTRO" == "nixos" ]; then
+    echo "NixOS detected: development tools are managed declaratively"
+    echo "via nixos/flake.nix and nixos/home.nix."
+    echo ""
+    echo "The following packages are already configured in the flake:"
+    echo "  - Go           (go, gopls, delve)"
+    echo "  - Ruby on Rails (ruby, bundler, rails, rbenv, nodejs)"
+    echo "  - Python        (python3, pip, virtualenv)"
+    echo "  - Neovim        (latest)"
+    echo "  - Cloud/DevOps  (kubectl, k9s, terraform, helm, awscli2)"
+    echo "  - Other tools   (oh-my-posh, fzf, bat, eza, ripgrep, fd)"
+    echo ""
+    echo "Run the main-setup.sh NixOS workflow or apply manually:"
+    echo ""
+    echo "  sudo nixos-rebuild switch --flake ~/dotfiles/nixos#nixos"
+    echo "  home-manager switch --flake ~/dotfiles/nixos#blake"
+    echo ""
+    echo "Skipping imperative dev tools setup."
+    echo "--- Development Tools Setup Finished ---"
+    exit 0
+fi
+
+# ═══════════════════════════════════════════════════════════
+#  TRADITIONAL DISTRO PATH (Fedora / Ubuntu / Debian / Pop)
+# ═══════════════════════════════════════════════════════════
+
 # Setup NVIM
 echo "Setting up Neovim..."
 _nvim_asset_name() {
@@ -140,21 +174,68 @@ else
   echo "✔ Oh-My-Posh already installed: $(oh-my-posh --version | head -n1)"
 fi
 
-# Install Rust Up
-echo "Installing Rust via rustup..."
-if command -v rustc &>/dev/null; then
-    echo "Rust (rustc) already installed."
+# ── Ruby on Rails ──────────────────────────────────────────
+echo ""
+echo "--- Setting up Ruby on Rails ---"
+
+if ! command -v ruby &>/dev/null; then
+  echo "➤ Installing Ruby via rbenv..."
+
+  # Install rbenv
+  if [ ! -d "$HOME/.rbenv" ]; then
+    git clone https://github.com/rbenv/rbenv.git "$HOME/.rbenv"
+    git clone https://github.com/rbenv/ruby-build.git "$HOME/.rbenv/plugins/ruby-build"
+    echo 'export PATH="$PATH:$HOME/.rbenv/bin"' >> "$HOME/.bashrc"
+    echo 'export PATH="$PATH:$HOME/.rbenv/bin"' >> "$HOME/.zshrc"
+    echo 'eval "$(rbenv init -)"' >> "$HOME/.bashrc"
+    echo 'eval "$(rbenv init -)"' >> "$HOME/.zshrc"
+    echo "rbenv installed. A new shell is needed or run:"
+    echo "  export PATH=\"\$PATH:\$HOME/.rbenv/bin\" && eval \"\$(rbenv init -)\""
+  else
+    echo "rbenv already installed."
+  fi
+
+  # Install Ruby latest stable via rbenv
+  export PATH="$PATH:$HOME/.rbenv/bin"
+  eval "$(rbenv init - bash 2>/dev/null || true)"
+
+  if command -v rbenv &>/dev/null; then
+    RUBY_LATEST=$(rbenv install -l 2>/dev/null | grep -v - | tail -1)
+    if [ -n "$RUBY_LATEST" ]; then
+      echo "➤ Installing Ruby ${RUBY_LATEST} (this may take a while)..."
+      rbenv install "$RUBY_LATEST"
+      rbenv global "$RUBY_LATEST"
+      echo "Ruby ${RUBY_LATEST} installed and set as global version."
+    fi
+  fi
 else
-    # The -y flag automates the installation, --no-modify-path prevents it from altering .profile/.bashrc directly
-    # You'll need to source "$HOME/.cargo/env" or add it to your shell's config manually
-    curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --no-modify-path
-    echo "Rust installed via rustup. Source \"\$HOME/.cargo/env\" or add it to your shell config."
-    echo "For the current session, you can run: source \"\$HOME/.cargo/env\""
+  echo "✔ Ruby already installed: $(ruby --version 2>/dev/null | head -n1)"
+fi
+
+# Install Bundler
+if command -v gem &>/dev/null; then
+  if ! command -v bundler &>/dev/null; then
+    echo "➤ Installing Bundler..."
+    gem install bundler
+    echo "Bundler installed."
+  else
+    echo "✔ Bundler already installed."
+  fi
+
+  # Install Rails
+  if ! command -v rails &>/dev/null; then
+    echo "➤ Installing Rails..."
+    gem install rails
+    rbenv rehash 2>/dev/null || true
+    echo "Rails installed."
+  else
+    echo "✔ Rails already installed: $(rails --version 2>/dev/null | head -n1)"
+  fi
 fi
 
 echo "--- Development Tools Setup Finished ---"
 
-# --- Helm (Kubernetes package manager) ---
+# ── Helm (Kubernetes package manager) ──────────────────────
 echo ""
 echo "--- Installing Helm ---"
 if command -v helm &>/dev/null; then