Fix buffer resizing overflow and introduce safe power-of-two capacity growth

[bernardladenthin]

• Previously, calculating next capacity for large values like 1_073_741_824 caused overflow and returned Integer.MIN_VALUE.
• Rewrote ensureCapacity to use Long for arithmetic to guard against exceeding Int.MAX_VALUE.
• Introduced nextPowerOfTwoCapacity(minCapacity: Int) to safely calculate the next power-of-two ≥ minCapacity.
• Capped capacity at Int.MAX_VALUE to prevent buffer allocation errors.
• Added comprehensive unit tests covering negative, small, exact, and large input values to validate correct capacity growth behavior.

Note: You can compare the fixed behavior with the old logic using:

fun nextPowerOfTwoCapacity(minCapacity: Int): Int {
    return minCapacity.takeHighestOneBit() shl 1
}

[bernardladenthin]

Wrong branch, new PR in #2985