chore(test): add jest coverageThreshold gate (per-repo baseline-aware)

Locks in the current coverage floor so regressions fail CI. Threshold
is set just below today's measured floor so the gate is informative,
not punitive — fresh contributors see the same numbers green.

Author: heznpc

package.json

@@ -10,7 +10,7 @@
     "android": "expo start --android",
     "ios": "expo start --ios",
     "lint": "eslint app/ lib/",
-    "test": "jest --verbose --passWithNoTests",
+    "test": "jest --verbose --passWithNoTests --coverage",
     "version:patch": "node scripts/bump-version.js patch",
     "version:minor": "node scripts/bump-version.js minor",
     "version:major": "node scripts/bump-version.js major"
@@ -39,6 +39,14 @@
     "preset": "jest-expo",
     "transformIgnorePatterns": [
       "node_modules/(?!((jest-)?react-native|@react-native(-community)?)|expo(nent)?|@expo(nent)?/.*|@expo-google-fonts/.*|react-navigation|@react-navigation/.*|@sentry/react-native|native-base|react-native-svg)"
-    ]
+    ],
+    "coverageThreshold": {
+      "global": {
+        "statements": 75,
+        "branches": 55,
+        "functions": 70,
+        "lines": 80
+      }
+    }
   }
 }