test: cover STATS output end to end

[autoblitzbot]

Summary

• execute the real info.stats.sh end to end with synthetic maker history
• assert rolling day/week/month earnings and coinjoin counts
• assert lifetime all totals are calculated once per maker event, without adding overlapping periods
• mock a running Yield Generator and assert its elapsed uptime is rendered
• document the new regression coverage

Finding

The reported lifetime-total bug is not reproducible on current master. The implementation already increments lifetime totals directly once per maker row. The new fixture makes this explicit: 100/200/300/400-sat events render day/week/month/all totals of 100/300/600/1000 and counts of 1/2/3/4.

The controlled running-maker case also renders 1d:2h:3m. The field report may depend on the live process command/environment; #135 tracks a known Jam-specific uptime case. This PR adds the missing regression harness without speculative production changes.

Closes #200.

Tests

• bats tests/info.stats.bats — 1/1 pass
• bats -r tests — 62/62 pass