Harden API error handling and clean no-useless-catch

[sugan0tech]

Summary
Standardize API error handling and remove no-useless-catch by letting Axios errors map to a single ApiError path.

Context
In src/utils/api.ts:

• handleApiError throws, but many call sites use return handleApiError(err), which is misleading and may confuse types/control flow.
• Some try/catch blocks only rethrow, triggering no-useless-catch.

Tasks

• Replace return handleApiError(err) with throw handleApiError(err) or just let the error bubble if no mapping is needed.
• Remove try/catch wrappers that merely rethrow.
• Align function signatures and docs: helpers throw ApiError on failure.
• Audit callers to ensure errors are caught where UX shows toasts or error states.

Acceptance Criteria

• npm run lint passes with no-useless-catch resolved.
• Consistent, typed throw behavior across API helpers; no silent returns on failure.
• Error toasts/messages still display meaningful content for users.