fix: ble write handling

[krushnarout]

Android processes only one ble write at once, that’s why it was crashing

fix: added sequential queue, timeout, and busy error handling

closes #3440

[gemini-code-assist]

Code Review

This pull request introduces a sequential write queue with retry logic to handle BLE write limitations on Android. The implementation correctly serializes write operations and adds robustness with timeouts and exponential backoff for retries. My review includes one suggestion to improve the robustness of the error-checking logic for retries, to avoid potential false positives from a broad string match.

[gemini-code-assist]

The string check msg.contains("201") is a bit fragile and could lead to incorrectly retrying on errors that are not retryable. For example, it could match parts of other numbers in an error message (e.g., a different error code like 1201, or part of a memory address). To make this more robust, consider using a more specific pattern, for example by checking for word boundaries.

Suggested change

	return msg.contains("busy") || msg.contains("201");
	return msg.contains("busy") || RegExp(r'\b201\b').hasMatch(msg);

[beastoin]

where are the tests sir ?

@krushnarout