v0.1.30 - Throughput overview today-only mix cards; mix formula save 500 fix

Throughput Overview: Horse Mix and Grain Mix are now the first two cards and
show TODAY's output only. Removed the 7d/4w/6w/12w range selector; the cards
are fixed to Horse mix today, Grain mix today, Today, This week, 4-week average.

Mix Editor formula save: fix HTTP 500 on PUT /editor/mixes/{id}/formula. The
audit-diff path read the resolved formula by attribute, but the resolver returns
dicts -> AttributeError. Read by key and expire stale ORM state so the response
reflects the just-saved rows. Adds regression tests for both save branches.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "hunter-backend"
-version = "0.1.29"
+version = "0.1.30"
 description = "Costing platform MVP backend (API for Hunter)"
 requires-python = ">=3.11"
 dependencies = [