[TASK][Timpani-n] Handle timer overruns gracefully

[LGSI-KarumuriHari]

📝 Task Description

Detect and handle missed timer activations due to overload.

📋 Checklist

• Detect timer overruns using timer_getoverrun()
• Log overrun events
• Skip missed activations or reschedule
• Update task release times correctly
• Report overruns to monitoring system
• Implement overrun recovery strategy

🔗 Related Requirement

Relates to #27 (Scheduler Logic)
Relates to deadline miss detection

📐 Implementation Guidelines

• Functional Requirement: FR-8.2.3 - Handle timer overruns gracefully
• Component: timpani-n/Execution Layer/Timer Manager
• Check timer_getoverrun() after each expiration
• Skip overrun activations (don't try to catch up)
• Log overrun count and affected tasks
• Consider overrun as potential deadline miss

🧪 Testing Method

• Unit test: Simulate overrun conditions
• Integration test: Test overrun handling under load
• Recovery test: Verify correct resumption after overrun