Directional observers

An observer has two important faces:

| Face | Vanilla look | Meaning |
| --- | --- | --- |
| Front (`observer_front`) | The "lens" / face plate | **Detection** — watches this side |
| Back (`observer_back`) | Flat plate with a red dot | **Output** — pulses redstone from here |

The third-person camera rarely gives you a clean look at both at once, so it is
easy to place an observer backwards and spend ten minutes debugging a circuit
that never fires.

This pack paints a **high-contrast red arrow on all four side faces**
(`up`, `down`, `east`, `west`). Every arrow points **from the detection lens
toward the output dot**, so the block's signal direction is readable at a glance
from any angle.

### Glowing pulse ring

When the observer is powered, the back face shows the usual blinking red dot.
This pack adds an **emissive halo + hot core** around that dot, rendered at full
brightness via the 26.3 element-level `light_emission` field. The result reads
clearly in dark rooms, in caves, and through dark-tinted glass.

The unpowered back dot, and the front lens, are left completely vanilla.