Fix Timer._timer_count to increment the class variable, not instance

[bysiber]

Summary

Fix Timer._timer_count to actually increment the class variable instead of creating a shadowing instance attribute.

Problem

class Timer:
    _timer_count: int = 1  # Class variable

    def __init__(self, ...):
        self.name = f"Timer#{self._timer_count}" if name is None else name
        self._timer_count += 1  # Bug: creates instance attribute, class var stays 1

In Python, self._timer_count += 1 reads the class variable (1), adds 1 (2), and stores the result as an instance attribute on self. The class variable Timer._timer_count is never modified — it stays at 1 forever.

Every auto-named timer gets the name "Timer#1".

Fix

Use Timer._timer_count += 1 (explicit class reference) to modify the class variable directly.

[willmcgugan]

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