Add "satya-explorer" CLI/TUI for browsing audit logs

Satya stores detailed audit logs in a lightweight backend (flat files or SQLite), but exploring them currently requires either using the dashboard or writing custom queries/scripts. Power users and infra folks often prefer quick, terminal-based exploration.

A small `satya-explorer` CLI/TUI would make it easier to inspect agent activity and debug workflows directly from the terminal.

Task
----

Design and implement a read-only CLI (and optional TUI) that can:

1. Connect to the existing Satya storage:
- SQLite DB if configured
- otherwise the default flat-file store

2. Provide useful filters:
- by agent name
- by task status / error flags
- by time range
- by tags / labels

3. Render concise outputs:
- list tasks with status and timestamps
- show full details for a single task (events, messages, etc.)

Implementation Steps
--------------------

- [ ] Decide on CLI structure and add an entry point via `pyproject.toml` / `setup.cfg`
- [ ] Implement read-only queries for SQLite and file-backed storage
- [ ] (Optional) Add a minimal TUI view using a Python TUI library
- [ ] Add docs: **"Inspect Satya audit logs from your terminal"** and link from the main `README.md`

Resources
---------

- • Audit log schema / storage implementation in this repo
- • Existing logging / ROI features described in docs

Why This Matters
----------------

A terminal-first explorer is great for demos, debugging, and social posts (screenshots/GIFs), and it appeals to contributors who enjoy building observability tooling.