Fix timer calculations mixing Stopwatch and TimeSpan ticks

[DevD4v3]

Problem

The timer implementation mixes two different time units:

• Stopwatch.GetTimestamp(), which returns timestamps expressed in Stopwatch ticks (Stopwatch.Frequency ticks per second).
• TimeSpan.Ticks, which uses a fixed resolution of 10,000,000 ticks per second.

These values are currently used interchangeably when scheduling timers.

Example

nextTick = Stopwatch.GetTimestamp() + interval.Ticks;

Here Stopwatch.GetTimestamp() is expressed in Stopwatch ticks, while interval.Ticks is expressed in TimeSpan ticks. These are different units and should not be combined directly.

This issue is less visible on Windows because Stopwatch.Frequency commonly matches TimeSpan.TicksPerSecond (10,000,000).

On Linux, however, Stopwatch.Frequency is typically much higher (for example 1,000,000,000), causing timer intervals to be interpreted incorrectly.

For example:

TimeSpan:
1 second = 10,000,000 ticks

Stopwatch (Linux):
1 second = 1,000,000,000 ticks

As a result, a 1-second interval is interpreted as:

10,000,000 / 1,000,000,000 = 0.01 seconds

which causes timers to execute approximately 100× faster than expected.

Solution

Convert TimeSpan values to Stopwatch ticks before storing or comparing them:

var intervalTicks =
    (long)(interval.TotalSeconds * Stopwatch.Frequency);

This ensures that all timer calculations use the same unit (Stopwatch ticks) and behave consistently across platforms.