This sketch is a minimal ESP32-C3 Opus codec smoke test.

What it does:
- Generates a sine wave locally
- Encodes it with Opus
- Decodes it immediately again
- Sends the decoded PCM to I2S

Why this example:
- It tests the raw Opus codec path without Ogg or CAN framing
- It is closer to the later Pi -> CAN -> ESP32 decoder path than MP3
- It keeps CPU load down by using 16 kHz mono and low encoder complexity

Expected hardware:
- ESP32-C3
- I2S DAC / amp on:
  - BCLK = GPIO 6
  - LRCK = GPIO 7
  - DIN = GPIO 5

Required Arduino libraries:
- `arduino-audio-tools`
- `arduino-libopus`

If this sketch runs and outputs a stable sine tone, the basic Opus encode/decode
chain is working on the ESP32-C3.