brand: replace placeholder glyph with real Fitdays artwork, bump to 1.0.3

frenck's hacs/default review was against v1.0.0; the homeassistant floor
and the README wording on body-composition/heart-rate sensors going
unknown were already fixed by then. The remaining item was brand assets:
custom_components/fitdays/brand/ held only a placeholder icon, no logo.
Replace it with the real teal icon and logo (1x/2x, no dark variant
needed) and update the README note that called it a placeholder.

Author: AboveColin

README.md

@@ -93,8 +93,9 @@ device). On a scale without it the sensor stays *unknown*, not *unavailable*.
   unknown for that weigh-in rather than holding their previous value, and the
   `weight_only` attribute on the weight sensor says why.
 - The integration is read-only. It never writes to your Fitdays account.
-- Brand artwork in `custom_components/fitdays/brand/` is a generic placeholder
-  glyph, not the vendor's logo. Home Assistant reads that folder from 2026.3.0
+- Brand artwork lives in `custom_components/fitdays/brand/` (icon and logo, at
+  1x and 2x). The Fitdays teal square works on light and dark, so there are no
+  separate dark-mode variants. Home Assistant reads that folder from 2026.3.0
   onward; on older cores the integration renders without an icon.
 
 ## Disclaimer

custom_components/fitdays/brand/icon.png

@@ -9,5 +9,5 @@
   "iot_class": "cloud_polling",
   "issue_tracker": "https://github.com/abovecolin/HA-Fitdays/issues",
   "requirements": ["fitdays==1.0.0"],
-  "version": "1.0.2"
+  "version": "1.0.3"
 }