Phase 3 sub-commit 3: examples/todo POC app, built via the makers

Standalone Composer/CMake project under examples/todo/ derived from the
skeleton, demonstrating every Phase 3 architectural primitive in a
non-trivial app. All cross-side wiring is maker-generated; no
handwritten bridge glue.

Generated and customised:

  - src/Entity/Todo.php — make:bridge:resource Todo (UUIDv7 id)
  - src/Controller/TodoController.php — make:bridge:resource Todo (CRUD)
  - src/Controller/MarkAllDoneController.php — make:bridge:command
    MarkAllDone, body filled in to flip done=true on every row
  - qml/TodoList.qml — make:bridge:resource Todo (starter ListView)
  - qml/TodoWindow.qml — make:bridge:window Todo, body customised to
    embed a read-only mirror of the same ReactiveListModel

The Phase 1 ping demo is dropped from this app — it doesn't fit the
todo flow and nothing in Main.qml references it.

Main.qml is the real list UI:

  - Add input + button (POST /api/todos with optimistic-friendly key).
  - Per-row CheckBox + delete button (PATCH/DELETE via
    todoModel.invoke() with `pending` role driving opacity).
  - "Mark all done" button (POST /api/mark-all-done).
  - "Open second window" button (Component { TodoWindow {} } pattern).

Build / run delegated to the same Makefile shape as the skeleton, with
SCRIPT_DIR/QT_BIN updated for the renamed binary (build/qml/todo).
composer.json's path repo points at ../../../framework/php (one level
deeper than the skeleton's path repo).

Verified end-to-end with offscreen QPA: POST/PATCH/DELETE on /api/todos
all round-trip, /api/mark-all-done flips every row, Mercure dual-
publishes on every change. Clean shutdown.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

examples/todo/README.md

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+# examples/todo
+
+The framework's POC application: a real Qt/QML todo app whose backend is a Symfony service generated entirely by the `make:bridge:*` makers. Demonstrates every architectural primitive in PLAN.md §13 Phase 3.
+
+## What's here that wasn't in the skeleton
+
+- `Todo` resource (entity + controller + QML snippet) generated via `make:bridge:resource Todo`.
+- `MarkAllDone` command generated via `make:bridge:command MarkAllDone`, with a body that flips `done = true` on every todo.
+- `TodoWindow.qml` second-window scaffold generated via `make:bridge:window Todo`, customised to embed a read-only mirror of the same `ReactiveListModel`.
+- `Main.qml` rewritten as a real list UI with add input, per-row toggle/delete, "mark all done", and "open second window".
+
+Everything cross-side (PHP ↔ QML) is maker-generated. There is no handwritten bridge glue in this example.
+
+## Run it
+
+```bash
+make install        # composer install
+make build          # cmake + qt host
+make doctor         # bridge:doctor — readiness check
+make dev            # FrankenPHP --watch + Qt host
+```
+
+Add a few todos, toggle them, click "Mark all done", click "Open second window" — both windows stay in sync.
+
+## Multi-window test
+
+1. `make dev` starts the app.
+2. Add three todos via the input field.
+3. Click **Open second window**. A `Todos (mirror)` window opens.
+4. In the main window, toggle one of the todos. The mirror flips its row within ~50 ms (Mercure SSE).
+5. Add a new todo in the main window. It appears in the mirror within ~50 ms.
+6. Click **Mark all done** in the main window. Both windows show all rows ticked simultaneously.
+
+Each window has its own `ReactiveListModel` instance subscribed to the same `app://model/todo` topic; the framework keeps them coherent without per-window glue.
+
+## Crash-and-recover test
+
+1. `make dev` is running.
+2. Add a todo so the list is non-empty.
+3. From another terminal: `pkill -f 'examples/todo/symfony.*frankenphp'`.
+4. The app's `AppShell` shows the **Reconnecting** banner (visible on the second window; the main window keeps its own status display).
+5. Restart the FrankenPHP child: from the example dir, `cd symfony && frankenphp run --watch --config ../Caddyfile` — or just re-run `make dev`.
+6. The app flips back to **Online** and re-fetches the list. No row corruption.
+
+## Layout
+
+```text
+todo/
+  Caddyfile           # FrankenPHP / Mercure config (port 8765, anonymous SSE)
+  Makefile            # build / dev / doctor / quality
+  scripts/dev.sh
+  symfony/
+    composer.json     # path repo points one level deeper at framework/php
+    config/
+    src/Entity/Todo.php                        # generated by make:bridge:resource
+    src/Controller/TodoController.php          # generated, CRUD on /api/todos
+    src/Controller/MarkAllDoneController.php   # generated, body filled in
+    public/index.php
+    bin/console
+    .env
+    migrations/
+  qml/
+    CMakeLists.txt
+    main.cpp
+    Main.qml          # real todo UI (add / toggle / delete / mark-all / 2nd-window)
+    TodoList.qml      # generated; also reused by the second window
+    TodoWindow.qml    # generated, customised to embed mirror list
+```
+
+## What this example proves
+
+- The headline workflow scales: a non-trivial app's PHP/QML wiring is **all generated**.
+- `ReactiveListModel` handles in-flight optimistic mutations (`pending` role drops opacity on toggled rows until the Mercure echo lands).
+- Two windows of the same QML app stay coherent under mutations from either side.
+- Stopping FrankenPHP mid-session triggers `Reconnecting` → `Offline` UI; restart restores `Online` and re-fetches without dupes.
+- `Idempotency-Key` round-trips through to Mercure as `correlationKey` — visible in `dev.log` if you `grep correlationKey`.
+
+## Out of scope here
+
+- A CI-driven version of the multi-window / crash-recover tests lives in Phase 3 sub-commit 4 as a bridge-integration suite.
+- No persistence options (export, backup) — same SQLite `var/data.sqlite` as the skeleton. Apps move to Postgres by overriding `DATABASE_URL`.