Add edge hardware requirements

docs/hardware/edge-device-requirements.md

@@ -0,0 +1,29 @@
+# Edge Device Hardware Requirements
+
+**Target Platform**: Raspberry Pi 5 + Cellular HAT
+
+## Must-Have Features
+
+- Raspberry Pi 5 (or equivalent)
+- Cellular connectivity (eSIM preferred for remote provisioning)
+- Ability to run a local hotspot during initial setup
+- Support for camera input (for analog gauge reading)
+- Low power consumption for always-on operation
+- Tamper-evident enclosure design
+- Easy access hatch for SIM/eSIM without opening main enclosure
+
+## Recommended Sensors (MVP)
+
+- Pressure sensors
+- Current / amp sensors (inductive)
+- Flow meters (pulse or analog)
+- Tank level sensors
+- Camera for analog dial/needle gauges (optional but supported)
+
+## Constraints
+
+- Must work in locations with no reliable Wi-Fi
+- Must minimize cellular data usage
+- Must support reliable local processing even during internet outages
+
+**Related**: See `architecture/overview.md` and `pumphouse-use-cases.md`.