v0.1.29 - Mix Editor % edits no longer rebalance other ingredients

Editing one ingredient's % now converts only that row to kg against the
Total mix anchor; other ingredients are left untouched (no proportional
redistribution). Removing a row likewise leaves the rest as-is. The hard
"percentages must total 100%" save guard is relaxed (kg is canonical and
the backend does not require 100%); the % chip remains as live feedback.

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 = "0.1.28"
+version = "0.1.29"
 description = "Costing platform MVP backend (API for Hunter)"
 requires-python = ">=3.11"
 dependencies = [