feat: install + OS integration + full test/bench pyramid + widget

[hyperpolymath]

Realises the "install Neurophone on phone, integrate with OS, deploy full
testing and benching" task end-to-end:

Build / deps

• Pin rand/rand_distr to versions compatible with ndarray-rand 0.16
  (workspace was previously broken: the rand 0.10/0.9 cross-version
  trait collision left lsm and esn uncompilable).

Subcrate implementations

• Replaced the sensors/, bridge/, llm/ stub crates with real but
  minimal implementations: per-channel IIR filters + windowed feature
  extractor; salience/urgency encoder with NL description; LlmBackend
  trait with a deterministic MockBackend so the rest of the workspace
  is testable without a 700 MB model file.

Testing pyramid (28 → 139 tests, 0 failures)

• Per-module unit tests in every crate.
• Point-to-point integration tests at crate boundaries.
• End-to-end pipeline tests through neurophone-core composing the real
  sensors + lsm + esn + bridge + llm crates.
• Aspect tests: concurrency (Arc<Mutex<...>>), timing, error paths,
  resource bounds.
• Lifecycle tests: init / start / run / shutdown / restart.

Bench coverage (8 criterion targets)

• sensors_bench, bridge_bench, llm_bench, claude_bench, esn_bench,
  lsm_bench (existing), neurophone_bench (existing), pipeline_bench
  (new E2E sensor → LLM step bench).
• TESTING-REPORT.adoc updated with median timings and frame-budget
  analysis (full non-LLM pipeline ~2.6 ms vs 20 ms 50 Hz budget).

Home-screen widget

• NeurophoneAppWidget (provider) + NeurophoneWidgetActions (state IPC)
  • NeurophoneWidgetConfigureActivity (first-run config).
• 3×2 cell layout: power toggle, refresh, salience progress bar,
  "Ask NeuroPhone" button.
• res/xml/neurophone_widget_info.xml, layout, drawables, strings.

OS integration

• NeurophoneService: foreground service that owns the sensor → neural
  → LLM loop, registers SensorManager listeners at SENSOR_DELAY_GAME,
  computes a salience signal and pushes it to the widget every 1 s.
• BootReceiver restarts the service after reboot if the user had it on.
• AndroidManifest wired with FOREGROUND_SERVICE_DATA_SYNC,
  POST_NOTIFICATIONS, RECEIVE_BOOT_COMPLETED, WAKE_LOCK; intent
  filters for ASSIST, ACTION_SEND text/plain, deep link
  neurophone://query?q=... .
• MainActivity.handleEntryIntent() handles widget tap / share / ASSIST
  / deep-link entry.
• scripts/install-on-phone.sh — workstation ADB installer (build APK,
  push model, grant runtime perms, start service).
• scripts/install-termux.sh — on-device Termux CLI installer.
• scripts/start-on-boot.sh — Termux:Boot hook.
• scripts/uninstall.sh — clean removal in either mode.
• docs/OS_INTEGRATION.adoc documents every integration surface.

Limitations

• Cannot physically install on the user's phone from this sandbox
  (no ADB / network path to a device); user runs install-on-phone.sh
  from their workstation. APK build itself requires Android NDK +
  SDK, which is not present in this environment, but all Rust code
  builds and tests cleanly on host.

https://claude.ai/code/session_012opuP3HehkjDkF1XQ8nFex