Limitcode 1.1.8 - Gemini/Anthropic hotfix (issue #10)

1.1.7 ended the chat turn with "Object of type EscapeGate is not JSON
serializable" when the provider passed tool arguments as a dict
(Gemini, Anthropic). The file edit itself had already been applied.

Tool arguments are now copied before the session escape gate is
injected, so the provider's original dict stays JSON-serializable.
