Banner: suppress low-qty alert when sibling product entries exist elsewhere

A partially-used fridge entry (e.g. 191 ml of milk) triggered a
'suspiciously low quantity' banner even when sealed packages of the
same product were present in another location (e.g. pantry).

Fix: before pushing a low-qty review alert, group all inventory rows
by product key (barcode, or name+brand fallback). If any sibling entry
for the same product has qty > 0 in a different row, skip the alert.
High-qty and suspicious package-size alerts are unaffected.

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased] - 2026-04-30
 
+### Fixed
+- **Low-qty banner false positive** — A "suspiciously low quantity" review alert is now suppressed for a partially-used inventory entry when one or more sibling entries for the same product (identified by barcode, or name+brand as fallback) exist in other locations with stock > 0. Prevents noise like "191 ml of milk" when 11 sealed packages are stored in the pantry.
+
 ### Changed
 - **Non-alarmist expired banner** — Banner icon, CSS class, and title suffix now adapt to the `getExpiredSafety()` level:
   - `ok` (long-life products, freezer within margin): green banner, ✅ icon, "— Scaduto (ancora ok)"