tools: add make analyze/test/doctor and unify gradle wrappers

- Add scripts/analyze_all.sh and scripts/test_all.sh that run flutter
  analyze/test across every app and report a summary
- Add scripts/repo_doctor.sh that flags config drift (sdk constraint,
  analysis_options, pubspec name, applicationId, gradle version, docs,
  tracked generated files) and exits non-zero for use as a pre-commit gate
- Wire these into the Makefile as 'make analyze/test/doctor' and document
  them in MAINTENANCE.md
- Bring bmi_calculator and push_notifications gradle wrappers up to the
  repo-standard 9.7.0; note push_notifications as a Firebase app requiring
  google-services.json

scripts/test_all.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Runs `flutter test` in every example app that has a test directory.
+# Exits non-zero if any test run fails.
+
+source "$(dirname "${BASH_SOURCE[0]}")/common.sh"
+
+passed=0
+failed=0
+skipped=0
+failed_apps=()
+
+run_tests() {
+	local dir="$1"
+	local app
+	app=$(basename "$dir")
+
+	if [ ! -d "$dir/test" ]; then
+		skipped=$((skipped + 1))
+		return
+	fi
+
+	if (cd "$dir" && flutter test >/dev/null 2>&1); then
+		passed=$((passed + 1))
+	else
+		failed=$((failed + 1))
+		failed_apps+=("$app")
+	fi
+}
+
+separator
+echo "  Running flutter test for all Flutter apps:"
+for_each_app pubspec.yaml run_tests
+separator
+printf "  %-16s %s\n" "Passed:" "$passed"
+printf "  %-16s %s\n" "Failed:" "$failed"
+printf "  %-16s %s\n" "No tests:" "$skipped"
+if [ "${#failed_apps[@]}" -gt 0 ]; then
+	echo "  Failed apps:"
+	printf "    %s\n" "${failed_apps[@]}"
+fi
+separator
+
+[ "$failed" -eq 0 ]