v1.7.0

v1.7.0 — integration patch + research-derived follow-conversion gates

Embeds the multi-agent follow-conversion playbook into preflight, config
check, engage recommend, inspire, and metrics. Bakes in the rules so users
don't have to memorize them.

New preflight gates: weak_hook_no_weight (Hook), reference_only_risk
(Substance) — catches the doublenickk trap, multiple_ctas (Substance) —
Welsh's one-ask rule. Issue now carries a group field for action-oriented
UX without breaking the JSON contract.

Bio audit in config check scans against the 4-element follow-conversion
formula. inspire freshness annotation prevents near-duplicate reposts.
metrics adds profile_click_rate_per_1k + bookmark_to_like_ratio as
leading follow-conversion indicators. engage recommend deprioritizes
sub-500-follower targets (Grox spam-classifier bucket). Home-timeline
endpoint URL bug fixed.

Zero new commands. Zero new flags. ~440 LOC across 9 files. 95 unit + 29
integration tests pass; clippy -D warnings clean.