input validation and removal of unsafe numeric parsing

[metsw24-max]

This change hardens balancer-manager parameter handling by replacing permissive numeric parsing atoi atof with strict range-checked parsing
It ensures malformed or partially valid inputs are rejected instead of being silently coerced into valid values.

[metsw24-max]

@notroj look into this

[notroj]

I'll be brutally honest here @metsw24-max - the effect of these comments putting pressure on me to merge your patches is that I will trust you less, and take more time to review your work, not to merge them faster. You're a new contributor here, and we definitely appreciate your PRs. We're under high workload at the moment, give us time.

[metsw24-max]

apologies for that i didn’t mean to put any pressure on the review process. I understand the workload and appreciate you taking the time to review. I will wait for your feedback.