docs: align README and dual-render images with revised theme-agnostic rules

README.md

@@ -1,6 +1,6 @@
 ESP32-S3 vehicle telemetry and GPS tracker streaming location and vehicle status over Cat-M/NB-IoT cellular networks.
 
-![hero](docs/images/hero.jpg)
+![Waveshare SIM7080G Cat-M / NB-IoT cellular and GNSS modem module](docs/images/hero.png)
 
 **Status: in progress**
 

docs/images/README.md

@@ -1,5 +1,7 @@
 # Hardware Images Manifest
 
-`hero.jpg` — Treated hero banner (1600×1000px, `#0b0d10` dark theme canvas with left gradient fade) showing the Waveshare SIM7080G Cat-M / NB-IoT cellular and GNSS hardware assembly.
+`hero.png` — Transparent background cut-out of the Waveshare SIM7080G Cat-M / NB-IoT cellular and GNSS modem module for theme-agnostic README rendering. Source: Waveshare PICO-SIM7080G product page.
 
-`sim7080g-lte-module.jpg` — Waveshare Pico SIM7080G Cat-M / NB-IoT module, used with the ESP32-S3 for cellular connectivity in this tracker. Source: Waveshare PICO-SIM7080G product page.
+`hero-site.webp` — Portfolio dark-canvas render (1600×1000px, `#0b0d10` canvas with left gradient fade and `#8ecbff` rim light) for the portfolio resume site.
+
+`sim7080g-lte-module.jpg` — Original source product image of the Waveshare Pico SIM7080G Cat-M / NB-IoT module used for the cellular link. Source: Waveshare PICO-SIM7080G product page.