Remove dead code

- wire.with_figure: the device uses dataclasses.replace directly.
- DeviceConnected/DeviceDisconnected: emitted, never subscribed to, and a duplicate
  of ConnectionChanged(target="firmware").
- ScreenService.toggle(): never called.
- GET /api/lirc (LircConfigOut, api.lircConfig): no front-end reads it.
- POST /api/volume's delta_percent (api.nudgeVolume): no front-end sends it.
- LibraryCache.shrink_stored_covers: a one-off migration that re-read every cover
  header on every scan. _INDEX_VERSION 7 rebuilds any cache that could still need it.
- Firmware: the MFRC522 library and its unused globals (lib/nfc/rc522.c is the
  driver in use), and mfrc_version.h, a reader test sketch nothing included.

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

python-backend/musicmouse/services/screen.py

@@ -141,9 +141,6 @@ class ScreenService:
         self._running = asyncio.create_task(self._run(command, sound=sound), name="screen")
         return True
 
-    async def toggle(self) -> None:
-        await self._run(self.config.toggle_command, sound=True)
-
     async def _run(self, command: str, *, sound: bool) -> None:
         argv = shlex.split(command)
         try:

python-backend/musicmouse/services/web/api.py

@@ -46,7 +46,6 @@ from musicmouse.services.web.schemas import (
     HaConfigOut,
     HaDeviceOut,
     LibraryOut,
-    LircConfigOut,
     PlayerStateOut,
     PlayIn,
     RemoteMappingIn,
@@ -68,7 +67,6 @@ from musicmouse.services.web.schemas import (
 from musicmouse.services.web.settings import (
     read_settings,
     to_device_volume,
-    to_percent,
     write_settings,
 )
 from musicmouse.services.web.state import snapshot
@@ -234,18 +232,10 @@ def build_router(
             return emit(
                 VolumeChangeRequested(delta=general.volume_increment * body.steps, source="web")
             )
-        if body.percent is not None:
-            target = body.percent
-        elif body.delta_percent is not None:
-            target = to_percent(app.player.volume, general) + body.delta_percent
-        else:
-            raise HTTPException(
-                status_code=422, detail="percent, delta_percent or steps required"
-            )
+        if body.percent is None:
+            raise HTTPException(status_code=422, detail="percent or steps required")
         return emit(
-            SetVolumeRequested(
-                volume=to_device_volume(max(0, min(100, target)), general), source="web"
-            )
+            SetVolumeRequested(volume=to_device_volume(body.percent, general), source="web")
         )
 
     # ------------------------------------------------------------- parent mode
@@ -321,12 +311,6 @@ def build_router(
 
     # -------------------------------------------------------------- IR remote
 
-    @router.get("/lirc")
-    def get_lirc_config() -> LircConfigOut:
-        if app.config.general.lirc is None:
-            raise HTTPException(status_code=404, detail="lirc not configured")
-        return LircConfigOut(connected=app.state.lirc_connected)
-
     @router.post("/remote/press/{digit}", status_code=204)
     def press_remote(digit: Digit) -> Response:
         # A keyboard's number keys, doing what the IR remote's do. An unassigned key

python-backend/musicmouse/services/web/schemas.py

@@ -26,7 +26,6 @@ __all__ = [
     "HaConfigOut",
     "HaDeviceOut",
     "LibraryOut",
-    "LircConfigOut",
     "PlayIn",
     "PlayerStateOut",
     "RemoteMappingIn",
@@ -261,15 +260,13 @@ class SeekIn(BaseModel):
 
 
 class VolumeIn(BaseModel):
-    """An absolute percentage, a relative percentage, or a number of steps; exactly
-    one of the three.
+    """An absolute percentage or a number of steps; exactly one of the two.
 
     ``steps`` moves by ``volume_increment`` device units per step - the same step the
     IR remote's volume keys and the rotary encoder take - rather than by a percentage.
     """
 
     percent: int | None = Field(default=None, ge=0, le=100)
-    delta_percent: int | None = Field(default=None, ge=-100, le=100)
     steps: int | None = Field(default=None, ge=-10, le=10)
 
 
@@ -325,13 +322,6 @@ class HaConfigOut(BaseModel):
     scenes: list[HaDeviceOut]
 
 
-class LircConfigOut(BaseModel):
-    """Presence-only, like ``HaConfigOut``: there is nothing secret in a host/port,
-    but the frontend only needs to know whether the remote is set up and connected."""
-
-    connected: bool
-
-
 class RemoteSlotOut(BaseModel):
     digit: str
     target_kind: Literal["album", "series"]