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/up.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+# Starts the development server (infra/dev/compose.yaml), waits for GET /health and prints the URLs.
+# KVITT_PUBLIC_URL defaults to http://<Mac LAN address>:<port> when the env file leaves it empty.
+# Usage: infra/dev/up.sh            Stop with: infra/dev/up.sh --down
+set -euo pipefail
+# shellcheck source=lib.sh
+. "$(dirname "$0")/lib.sh"
+
+if [[ "${1:-}" == "--down" ]]; then
+  compose down
+  exit 0
+fi
+
+port="$(dev_port)"
+lan="$(lan_address || true)"
+
+public_url="$(env_value KVITT_PUBLIC_URL)"
+if [[ -z "$public_url" ]]; then
+  if [[ -n "$lan" ]]; then public_url="http://$lan:$port"; else public_url="http://localhost:$port"; fi
+fi
+export KVITT_PUBLIC_URL="$public_url"
+
+data_dir="$(dev_path "$(env_value KVITT_DEV_DATA_DIR)")"
+secrets_dir="$(dev_path "$(env_value KVITT_SECRETS_DIR)")"
+mkdir -p "$data_dir"
+if [[ ! -f "$secrets_dir/fcm-service-account.json" ]]; then
+  echo "up.sh: no $secrets_dir/fcm-service-account.json; the server starts with push disabled." >&2
+fi
+
+compose up -d server
+
+echo "Waiting for http://localhost:$port/health ..."
+for _ in $(seq 1 30); do
+  if body="$(curl -fsS "http://localhost:$port/health" 2>/dev/null)"; then
+    echo "health: $body"
+    echo "Mac:     http://localhost:$port"
+    [[ -n "$lan" ]] && echo "Phone:   http://$lan:$port   (home Wi-Fi)"
+    echo "Invites: $public_url"
+    exit 0
+  fi
+  sleep 1
+done
+echo "up.sh: /health did not answer within 30 s; see infra/dev/logs.sh" >&2
+exit 1