feat: add android-fs5 CLI toolset

- fs5 entrypoint with status, push, pull, app, shell, logs commands
- lib/adb.sh: ADB wrapper functions with idempotency and --force guards
- lib/output.sh: human + JSON output formatting via Python
- 33 bats tests (6 status, 9 transfer, 7 app, 5 shell, 6 logs) — all passing
- Zero shellcheck warnings
- .env-based config (device serial, log path)
- Spec-Driven Development artifacts in specs/001-android-fs5-management/

Device: exone GmbH FS5 (RD51QE202392, Android 9)

tests/test_shell.bats

@@ -0,0 +1,43 @@
+#!/usr/bin/env bats
+# tests/test_shell.bats — Tests for 'fs5 shell' command (US4)
+
+bats_require_minimum_version 1.5.0
+
+SCRIPT="${BATS_TEST_DIRNAME}/../fs5"
+
+setup() {
+  export DEVICE_SERIAL="RD51QE202392"
+  export LOG_FILE="/tmp/fs5-test-$$.log"
+}
+
+teardown() {
+  rm -f "${LOG_FILE}"
+}
+
+@test "shell: executes echo command on device" {
+  run "${SCRIPT}" shell "echo hello-from-device"
+  [ "${status}" -eq 0 ]
+  [[ "${output}" == *"hello-from-device"* ]]
+}
+
+@test "shell: forwards exit code from device command" {
+  run "${SCRIPT}" shell "exit 0"
+  [ "${status}" -eq 0 ]
+}
+
+@test "shell: returns device hostname/uname" {
+  run "${SCRIPT}" shell "uname -s"
+  [ "${status}" -eq 0 ]
+  [[ "${output}" == *"Linux"* ]]
+}
+
+@test "shell: --help shows usage" {
+  run "${SCRIPT}" shell --help
+  [ "${status}" -eq 0 ]
+  [[ "${output}" == *"shell"* ]]
+}
+
+@test "shell: exits with code 2 when device not connected" {
+  DEVICE_SERIAL="INVALID_SERIAL_000" run "${SCRIPT}" shell "echo test"
+  [ "${status}" -eq 2 ]
+}