feat: load i2c-dev kernel module on startup (#14)

Ensure i2c-dev kernel module is loaded before initializing I2C communication to guarantee /dev/i2c-* device access. Add error handling and logging for module loading process.

Reviewed-on: https://gitea.pstruebi.xyz/auracaster/bumble-auracast/pulls/14

src/auracast/server/multicast_server.py

@@ -146,6 +146,25 @@ _stream_lock = asyncio.Lock()  # serialize initialize/stop_audio on API side
 
 
 async def _init_i2c_on_startup() -> None:
+    # Ensure i2c-dev kernel module is loaded (required for /dev/i2c-* access)
+    try:
+        proc = await asyncio.create_subprocess_exec(
+            "sudo", "modprobe", "i2c-dev",
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE,
+        )
+        stdout, stderr = await proc.communicate()
+        if proc.returncode != 0:
+            log.warning(
+                "modprobe i2c-dev failed (rc=%s): %s",
+                proc.returncode,
+                (stderr or b"").decode(errors="ignore").strip(),
+            )
+        else:
+            log.info("i2c-dev module loaded successfully")
+    except Exception as e:
+        log.warning("Exception running modprobe i2c-dev: %s", e, exc_info=True)
+
     # Table of (register, expected_value)
     dev_add = "0x4a"
     reg_table = [