refactor: carry out shade requests from one module behind a LoopQueue

HTTP routes and MQTT commands now both build a shade request and submit it
to the LoopQueue, which loop() drains into ShadeRequests. ShadeRequests
finds the shade or group, turns client positions into stored ones, checks
ranges and fills in default repeats, and reaches the shades through the
ShadeOps seam: SomfyShadeOps on the device, a recording fake in the native
tests. MqttCommands turns a .../set topic into a shade request.

Behaviour that changes:
- MQTT tiltTarget, mypos, myTiltPos and tiltPosition, and /setPositions,
  now honour flipPosition like the other routes.
- MQTT mypos keeps the favorite tilt (was set to 0) and myTiltPos keeps
  the favorite lift.
- repeat 0 on /shadeCommand means no repeats, as it did for groups; a
  JSON repeat over 127 is capped instead of wrapping to the default.
- Position corrections go through the setters, so MQTT publishes them.
- MQTT commands wait while the radio is full instead of being refused.
- The queue is drained every loop() pass and no longer from inside a
  GitHub firmware download.

WebCommand.h is replaced by LoopQueue.h and ShadeRequests.h. 45 new native
tests, 271 in all. Flash: esp32devdbg +976 bytes, esp32dev +1,380 bytes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/LOOP_QUEUE_PLAN.md

@@ -1,6 +1,6 @@
 # Plan: domain modules behind the LoopQueue
 
-**Status:** planned, nothing built yet.
+**Status:** steps 0 and 1 built (PRs #39 and #40); steps 2–5 planned.
 **Written:** 2026-10-15, against commit `e624a41` on `refactor/entry-points-outputs`. Terms are defined in [GLOSSARY.md](../GLOSSARY.md); the threading rule is [ADR-0002](adr/0002-loop-task-is-the-only-writer-of-the-shade-model.md).
 
 ## Why
@@ -118,6 +118,18 @@ Each step is a PR of its own that can be tested on the device. Each one runs `pi
 | 4 | Change fan-out with dirty bits, replacing publishing from the `p_*` setters. | writes that skip MQTT, `position` stuck at 50 |
 | 5 | Split `Web.cpp` into WebUiRoutes and ApiRoutes, and `MQTT.cpp`/`SomfyMqtt.cpp` into MqttCommands, an MQTT connection and MqttPublisher. Edit parsing stays in `SomfyJson.cpp`. | the glossary names land in the code |
 
+### Step 1: what changed in behaviour
+- **Flip handling is the same for every entry point.** MQTT `tiltTarget`, `mypos`, `myTiltPos` and `tiltPosition`, and `/setPositions` (which Home Assistant calls), now turn the position round for a shade with `flipPosition`, as the other routes always did.
+- **Setting the favorite over MQTT keeps the other half.** `mypos` on a shade with tilt keeps the favorite tilt; before, it set it to 0. `myTiltPos` keeps the favorite lift, or uses where the shade is when it has none.
+- **`repeat` means the same everywhere.** Left out or negative is the shade's or group's own repeats; 0 is no repeats. `/shadeCommand` used to read 0 as "the shade's own". A JSON `repeat` over 127 is capped; it used to wrap round to "the shade's own".
+- **Position corrections reach MQTT.** `/setPositions` and MQTT `position`/`tiltPosition` go through the setters, so they are published.
+- **MQTT commands go through the LoopQueue.** While the radio is full they wait instead of being refused, and they run in order with web requests. An MQTT command topic that isn't understood is logged.
+- **The LoopQueue is drained on every `loop()` pass**, with or without a network. It is no longer drained from inside a GitHub firmware download, so a restore can't reboot the device in the middle of one.
+
+`WebCommand.h` became `LoopQueue.h` (the item and the hold rule) and `ShadeRequests.h` (the request, the `ShadeOps` seam and the module). `SomfyShadeOps` is the device side of the seam. `entryPoints/MqttCommands` holds the topic parsing. There are 45 new native tests (271 in all).
+
+Flash: `esp32devdbg` 1,546,405 → 1,547,381 bytes, `esp32dev` 1,396,957 → 1,398,337 bytes.
+
 ### Step 0 on a device
 NVS stays at `0x9000`, so the rolling codes survive. The file system partition shrinks from `0xE0000` to `0xD0000`, and the existing LittleFS won't mount, because `LittleFS.begin()` doesn't format. So:
 1. Take a backup through `/backup`.