Improve robustness: replace sleep() with readiness checks, time-window RTC latency

[cagataycali]

Context

PR #56 review — two robustness improvements flagged by @awsarron.

1. Sleep replacement

time.sleep() for process startup should be replaced with polling + timeout.

2. RTC latency history robustness

deque(maxlen=100) is count-based. At 5000Hz covers 0.02s, at 0.001Hz covers 100000s. Should be time-window based.

Acceptance Criteria

• No bare time.sleep() for process startup — poll with timeout
• RTC latency tracking works correctly at 0.001Hz–5000Hz
• Tests for edge cases

Ref: PR #56 review threads