fix(acl): map NaN/\u00b1Infinity to JSON null instead of panicking

[thanhtoantnt]

closes #15477

What changed

From for serde_json::Value in crates/tauri-utils/src/acl/value.rs was calling serde_json::Number::from_f64(f).unwrap(). The JSON spec (RFC 8259 §6) does not permit non-finite
floats, so from_f64 returns None for NaN, +Infinity, and -Infinity — and the .unwrap() turns that into an unconditional panic.

  // before — panics for non-finite f64
  Value::Number(Number::Float(f)) => {
      serde_json::Value::Number(serde_json::Number::from_f64(f).unwrap())
  }

  // after — non-finite maps to null
  Value::Number(Number::Float(f)) => {
      match serde_json::Number::from_f64(f) {
          Some(n) => serde_json::Value::Number(n),
          None => serde_json::Value::Null, // NaN / ±Infinity are not valid JSON
      }
  }

Number::Float accepts any f64 via From, so non-finite values are constructible without error and the panic was the first signal that anything was wrong — potentially surfacing
at an unrelated call site well after the bad value was created.

Non-finite floats now produce serde_json::Value::Null, consistent with the IEEE 754 null-substitution convention used by many JSON serializers.

[Legend-Master]

As much as this is a problem, from how we use this today, a crash might be better than silently making it null here.