Fix TypeError when LLM returns JSON objects instead of strings for
history_entry or memory_update.
Changes:
- Update prompt to explicitly require string values with example
- Add type checking and conversion for non-string values
- Use json.dumps() for consistent JSON formatting
Fixes potential memory consolidation failures when LLM interprets
the prompt loosely and returns structured objects instead of strings.
- Replaces fragile input() hacks with robust prompt_toolkit.PromptSession
- Native support for multiline paste, history, and clean display
- Restores animated spinner in _thinking_ctx (now safe)
- Replaces boxed Panel with clean header for easier copying
- Adds prompt-toolkit dependency
- Adds new unit tests for input layer
