Add measured Raspberry Pi 5 (CPU) section

Numbers from the 2026-08-31 Raspberry Pi 5 sweep: LiteRT benchmark_model
(litert-cli-nightly 0.2.0.dev20260805), CPU/XNNPACK, 4 threads, 10 warm-up +
50 timed runs x 3 invocations per file, cooldown between invocations, thermal
throttle state verified 0x0 on every run. Median + spread, never single-shot.
Measurements are joined to this repo by exact .tflite file name.

README.md

@@ -129,6 +129,14 @@ Measured on a **Samsung Galaxy S26** (Snapdragon 8 Elite Gen 5 / SM8850, Hexagon
 
 GPU wiring: [GPU guide](https://github.com/john-rocky/hf-to-litertlm/blob/main/docs/android-gpu.md).
 
+## Raspberry Pi 5 (CPU)
+
+Measured on a Raspberry Pi 5 Model B Rev 1.1 (8 GB, Raspberry Pi OS 64-bit) with the LiteRT [`benchmark_model`](https://ai.google.dev/edge/litert/models/measurement) tool from litert-cli-nightly 0.2.0.dev20260805: CPU inference (XNNPACK, 4 threads), 3 invocations per file of 10 warm-up plus 50 timed runs (the tool caps a phase at 150 s, so very slow graphs run fewer — the Runs column is the actual timed total). The latency is the median across invocations; the spread is the min–max over all timed runs. No thermal throttling occurred during these runs (`vcgencmd get_throttled` stayed `0x0`).
+
+| File | Inference (median) | Spread (min–max) | Runs | Peak memory |
+|---|---:|---:|---:|---:|
+| `u2net_fp16.tflite` | 1,052.8 ms | 1,045.0–1,090.5 ms | 150 | 520 MB |
+
 ## License & attribution
 
 - License: **Apache-2.0** (© the U²-Net authors,