[07-Release] #260 v0.4.0 — in-app tool calling

Phase 2-B 릴리스. on-device Gemma 4 가 6 tool 로 카탈로그/습관 CRUD.

- pubspec.yaml: 0.3.0+3 → 0.4.0+4
- CHANGELOG.md: [0.4.0] 섹션 추가
- APK: app-release.apk 287MB
  SHA-256 6670da0c4e9bf5e826174ebc48088540867d877cf58699119a519e2ffb40ea3a

회귀: 154 passed (1 skip), flutter analyze clean.

Refs #260

app/pubspec.yaml

@@ -1,7 +1,7 @@
 name: life_helper
 description: "Huberman + Atomic Habits + Tiny Habits + If-Then. Local-first habit/checklist/todo."
 publish_to: 'none'
-version: 0.3.0+3
+version: 0.4.0+4
 
 environment:
   sdk: ^3.12.2