feat: accept script_body and parameters_schema in save-to-library flow

Previously save_to_library() hardcoded parameters_schema to empty and
always used session.latest_script. Now accepts optional overrides from
the frontend for parameterized script bodies.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/services/script_builder_service.py

@@ -323,6 +323,8 @@ async def save_to_library(
     share_with_team: bool,
     user_id: UUID,
     team_id: UUID | None,
+    script_body: str | None = None,
+    parameters_schema: dict | None = None,
 ) -> "ScriptTemplate":
     """Save the latest generated script to the Script Library as a ScriptTemplate."""
     import uuid as uuid_mod
@@ -361,8 +363,8 @@ async def save_to_library(
         name=name,
         slug=slug,
         description=description,
-        script_body=session.latest_script,
-        parameters_schema={"parameters": []},
+        script_body=script_body or session.latest_script,
+        parameters_schema=parameters_schema or {"parameters": []},
         default_values={},
         validation_rules={},
         tags=[session.language, "ai-generated"],