feat: Implement dependency checking and Git identity validation

lib/deps.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+# =============================================================================
+# lib/deps.sh
+# Dependency and environment validation.
+# =============================================================================
+
+check_deps() {
+  local missing=()
+  local required=(git git-crypt curl jq)
+
+  for cmd in "${required[@]}"; do
+    if ! command -v "$cmd" &>/dev/null; then
+      missing+=("$cmd")
+    fi
+  done
+
+  if [[ ${#missing[@]} -gt 0 ]]; then
+    error "Missing required tools: ${missing[*]}"
+    echo -e "\nInstall them using your package manager:"
+    echo "  Debian/Ubuntu: sudo apt install ${missing[*]}"
+    echo "  MacOS:         brew install ${missing[*]}"
+    exit 1
+  fi
+
+  success "Environment check passed: all required tools found."
+
+  if ! command -v bw &>/dev/null; then
+    warn "Optional tool 'bw' (Bitwarden CLI) not found. Vaultwarden integration will be manual."
+  fi
+}
+
+check_git_identity() {
+  if [[ -z "$(git config user.name)" || -z "$(git config user.email)" ]]; then
+    warn "Git identity not set globally. Scripts will attempt to use local config."
+  fi
+}