Adds a clap-derive Cli (topic argument, --log-level flag) so the
research loop is a proper command-line tool instead of a raw
env::args().nth(1) read. Logging is now opt-in: tracing only
initializes a subscriber when --log-level is passed, so the terminal
stays clean by default. When logging is off, each research phase
(researcher/reviewer/writer) shows an indicatif spinner instead, so
the user isn't staring at a blank terminal during the 1-3 minute
Gemma tool-calling turns.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
