feat(common): prevent useTimer.pause from storing negative remaining time

[qsysvcore]

Fix: useTimer.pause() stores a negative remaining time

Problem

pause() in packages/common/src/hooks/useTimer.ts decremented remainingTimeRef.current unconditionally, without clamping, and used startTimeRef.current even when no timer was running:

remainingTimeRef.current -= currentTime - startTimeRef.current;

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/2	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 1 Global minimum 0 Max 1 1 1 if commit is unverified 1 Sum 2
CODEOWNERS	🟡 See below

🟡 CODEOWNERS

Code Owner	Status	Calculation
ui-systems-eng-team	🟡 0/1	Denominator calculation Additional CODEOWNERS Requirement Show calculation Sum 0 0 From CODEOWNERS 1 Sum 1