update to fix uart comms issues in cc1200 modem control - WIP, don't merge yet.

[JKI757]

this PR makes two fixes:

problem 1:

• commandWithResponse marks isCommandWithResponse = true before sending a
  command so that the UART reader goroutine diverts incoming bytes into the
  cmdSource channel.
• If m.command(cmd) returns an error (e.g., serial write failure, timeout, or
  modem reset), the function returns without clearing isCommandWithResponse.
• The reader keeps routing every subsequent byte into cmdSource, while no
  goroutine reads from it any more. The buffered channel fills, processReceivedData
  blocks, and symbol traffic stops, making the gateway appear frozen.

fix:

• Added routeIncomingByte, a helper that centralises routing of incoming
  bytes either to the command-response channel or the RX pipeline without
  holding the mutex while sending.
• Hardened commandWithResponse with a defer that always clears the
  isCommandWithResponse flag and drains any stale bytes regardless of how the
  function exits.
• Retained the clearResponseBuf call before issuing a command so unexpected
  bytes from previous transactions cannot poison the next response.

problem 2:

• processReceivedData terminates if a single Read call returns an error. once this goroutine
  exits, no one services the UART so the modem is unresponsive.

fix:

• Keep the goroutine running on transient read failures by logging the error
  and retrying instead of breaking out of the loop.
• Treat io.EOF as a recoverable event with a short back-off.
• Use the new routeIncomingByte helper to fan bytes out safely and log when
  the RX pipeline is saturated.

[sp5wwp]

Are any of those issues fixed already?

[jancona]

These changes did not resolve the comms issues. With the new firmware protocol, they're now obsolete, so I'm closing this PR.