Initial ssr repository

Convert the legacy system_sync.sh and system_restore.sh into a modular
shareable repository:

- bin/ssr CLI dispatcher with install/sync/restore/schedule/config/status
- lib/ split: common, cloud, brew, mackup, macos
- Cloud provider abstraction (icloud, dropbox, googledrive, onedrive, custom)
- launchd template for scheduled daily sync (renderable via sed)
- ssr.conf.example with whitelisted KEY=VALUE config loader
- macos-defaults.sh extracted from inline block, overridable
- install.sh bootstrap symlinks CLI into ~/.local/bin
- README with usage, config table, migration map, security notes
- Original scripts archived under legacy/ for reference

Fixes vs originals: set -euo pipefail, quoted vars, find -print0,
spctl --global-disable (was --master-disable), MACOS=".macos" bug,
zero-width char before ln, Apple Silicon brew shellenv, config injection
hardening.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/common.sh

@@ -0,0 +1,82 @@
+#!/usr/bin/env bash
+# lib/common.sh — shared helpers (logging, errors, validation).
+# Sourced by all ssr commands. Never executed directly.
+
+set -euo pipefail
+
+# Resolve repo root from any sourced location.
+SSR_LIB_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SSR_ROOT="$(cd "${SSR_LIB_DIR}/.." && pwd)"
+export SSR_ROOT SSR_LIB_DIR
+
+# Colors only when stdout is a TTY (no ANSI in launchd logs).
+if [[ -t 1 ]]; then
+    SSR_C_RED=$'\033[31m'; SSR_C_GRN=$'\033[32m'
+    SSR_C_YLW=$'\033[33m'; SSR_C_BLU=$'\033[34m'
+    SSR_C_DIM=$'\033[2m';  SSR_C_RST=$'\033[0m'
+else
+    SSR_C_RED=""; SSR_C_GRN=""; SSR_C_YLW=""; SSR_C_BLU=""; SSR_C_DIM=""; SSR_C_RST=""
+fi
+
+ssr::ts() { date '+%Y-%m-%dT%H:%M:%S%z'; }
+
+ssr::log()  { printf '%s %s[INFO]%s  %s\n'  "$(ssr::ts)" "$SSR_C_BLU" "$SSR_C_RST" "$*"; }
+ssr::ok()   { printf '%s %s[OK]%s    %s\n'  "$(ssr::ts)" "$SSR_C_GRN" "$SSR_C_RST" "$*"; }
+ssr::warn() { printf '%s %s[WARN]%s  %s\n'  "$(ssr::ts)" "$SSR_C_YLW" "$SSR_C_RST" "$*" >&2; }
+ssr::err()  { printf '%s %s[ERR]%s   %s\n'  "$(ssr::ts)" "$SSR_C_RED" "$SSR_C_RST" "$*" >&2; }
+ssr::die()  { ssr::err "$@"; exit 1; }
+
+# Mirror to syslog if available so launchd runs are findable via `log show`.
+ssr::syslog() {
+    [[ -x /usr/bin/logger ]] || return 0
+    /usr/bin/logger -t "ssr" -- "$*" || true
+}
+
+ssr::require_macos() {
+    [[ "$(uname -s)" == "Darwin" ]] || ssr::die "ssr requires macOS (Darwin). Detected: $(uname -s)"
+}
+
+ssr::require_cmd() {
+    command -v "$1" >/dev/null 2>&1 || ssr::die "Required command missing: $1"
+}
+
+# Confirm prompt with optional timeout (returns 0 = yes).
+ssr::confirm() {
+    local prompt="${1:-Continue?}" timeout="${2:-0}" reply
+    if [[ "$timeout" -gt 0 ]]; then
+        read -r -t "$timeout" -n 1 -p "${prompt} [y/N]: " reply || reply=""
+    else
+        read -r -n 1 -p "${prompt} [y/N]: " reply || reply=""
+    fi
+    echo
+    [[ "${reply,,}" == "y" ]]
+}
+
+# Validate a path is safe (no traversal, no shell metas). Used before any FS op.
+ssr::validate_path() {
+    local p="$1"
+    [[ -n "$p" ]] || ssr::die "Empty path"
+    [[ "$p" != *$'\n'* && "$p" != *$'\0'* ]] || ssr::die "Path contains control chars"
+    case "$p" in
+        *..*) ssr::die "Path traversal rejected: $p" ;;
+    esac
+}
+
+ssr::ensure_dir() {
+    local d="$1"
+    ssr::validate_path "$d"
+    [[ -d "$d" ]] || mkdir -p "$d"
+}
+
+# Source config file if it exists. Validates that only known KEY=VALUE lines
+# are present to avoid arbitrary code execution from a tampered config.
+ssr::load_config() {
+    local cfg="${1:-${SSR_CONFIG:-$HOME/.config/ssr/ssr.conf}}"
+    export SSR_CONFIG="$cfg"
+    [[ -f "$cfg" ]] || return 0
+    if grep -Eq -v '^[[:space:]]*(#|$|[A-Z_][A-Z0-9_]*=)' "$cfg"; then
+        ssr::die "Config $cfg contains invalid lines (only KEY=VALUE allowed)"
+    fi
+    # shellcheck disable=SC1090
+    source "$cfg"
+}