v0.7.2

chore: release v0.7.2 — cross-module transitive imports

Ships the global import walker refactor: main.tb only has to name the
items it touches directly, and the compiler pulls every transitively-
referenced helper across file boundaries. Proof point is Carl Code's
main.tb, which shrinks from 35 → 29 explicit import items once
AgentProfile, SquadResult, pick_agent_names_for_task, resolve_squad,
print_squad_assembling, and print_squad_complete stop needing to be
named explicitly.

All 8 crates bumped to 0.7.2. 377 unit + 191 phase1 integration green.

Homebrew formula SHA256s will be updated post-CI once the release
workflow publishes artifacts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>