3c: hotmem playground (terminal UI)

[valiantone]

Summary

Terminal UI for interactive add/search/inspect. Makes demos and debugging instant without needing curl or a Python script.

Scope

• hotmem playground CLI subcommand
• Interactive mode: add memories, search, inspect results
• Could use rich or textual for a polished TUI
• Optional dep group: pip install hotmem[playground]

Acceptance Criteria

• Can add and search memories interactively
• Search results displayed with scores and formatting
• Works against a running server or directly against a DB file