M2c-dev: development compose stack, backup job, Firebase setup docs

infra/dev: compose stack on the Mac (server kvitt-server:dev, on-demand backup),
.env.example, build/up/logs/backup/copy-google-services scripts. No Caddy, no TLS
(debug builds accept http to private LAN addresses, AC-2.8). Bind-mounted data.
infra/backup: alpine 3.24.2 image and backup.sh (SPEC 10.9; Drive upload skipped
when RCLONE_FOLDER_ID is empty). infra/README.md for the dev stack and Firebase.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

infra/dev/copy-google-services.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+# Copies the Firebase config (both Android clients, se.hagstedt.kvitt and se.hagstedt.kvitt.debug) from
+# infra/secrets/google-services.json to android/app/google-services.json in this checkout. Both are git-ignored.
+# Usage: infra/dev/copy-google-services.sh [source checkout]   (default: this checkout; in a worktree, pass the main checkout)
+set -euo pipefail
+# shellcheck source=lib.sh
+. "$(dirname "$0")/lib.sh"
+
+src_root="${1:-$repo_root}"
+src="$src_root/infra/secrets/google-services.json"
+dst="$repo_root/android/app/google-services.json"
+
+[[ -f "$src" ]] || { echo "copy-google-services.sh: $src not found (created by the M2c-dev Firebase setup)." >&2; exit 1; }
+git -C "$repo_root" check-ignore -q "android/app/google-services.json" || {
+  echo "copy-google-services.sh: android/app/google-services.json is not git-ignored; refusing to copy." >&2
+  exit 1
+}
+mkdir -p "$(dirname "$dst")"
+cp "$src" "$dst"
+chmod 600 "$dst"
+echo "Copied google-services.json to $dst"