refactor: prevent TTL extension on mount, add SSR guardrail, fix null/undefined round-trip

[woozyking]

• Skip the initial post-hydration write via a firstRun ref; previously every mount re-serialized the hydrated value and reset expiry, silently extending TTL indefinitely for any component that remounted before expiration
• Guard all storage access behind an SSR-safe isBrowser check
• Wrap cached payloads in { value } so null/undefined survive round-trip (previously indistinguishable from a cache miss)
• Move TTL unit + argument validation out of the write path; compute once at configuration time and tighten type checks (reject NaN, Infinity, non-numbers)
• Replace SUPPORTED_HOOKS array with a Set for O(1) lookup and clearer intent
• Gate console.warn behind NODE_ENV !== "production" to silence prod noise
• Extract dropCache helper and reuse it from the memoized remove()