Update series definition to infer schema

The `series` function no longer requires an explicit schema. The element
type is now inferred at compile time from subsequent `push` calls using
Hindley-Milner type inference. This simplifies series creation and
aligns with the project's goal of making the untyped AST simple while
the system handles complexity.

src/ast/rtl/series/mod.rs

@@ -64,14 +64,14 @@ pub fn register(env: &Environment) {
                     let final_layout = RecordLayout::get_or_create(fields);
                     Value::Series(Rc::new(RecordSeries::new(final_layout, lookback_limit)))
                 }
-                _ => panic!("series expects a lookback_limit and a type keyword (:float, :int...) or a schema record (e.g., {{:price :float}})"),
+                _ => panic!("series: second arg must be a type keyword (:float, :int…) or a schema record ({{:field :type}})"),
             }
         },
-    ).doc("Creates a new series (ring buffer) with a defined layout and lookback limit.")
-     .description("First arg is the lookback limit (int), second is either a type keyword (:float, :int, :bool, :text, :datetime) or a schema record ({:field :type}).")
+    ).doc("Creates a new series (ring buffer) with the given lookback limit.")
+     .description("Takes a single lookback limit (int). The element type is inferred at compile time from subsequent push calls via HM type inference. The compiler injects a second schema argument automatically; the runtime also accepts an explicit schema for cases where inference is not possible.")
      .examples(&[
-         "(series 100 :float)",
-         "(series 200 {:price :float :volume :int})",
+         "(series 100)",
+         "(do (def s (series 5)) (push s 1.5) (s 0))",
      ]);
 
     // (push series value) -> Void