feat: safe area fix, delete from repo, add Mistral provider

- Wrap root layout with SafeAreaProvider, use useSafeAreaInsets in all
  screens so FAB/action bar/scroll content clear Android nav bar
- Add deleteIncidentFromGit() (Gitea/GitHub/GitLab) — detail screen now
  offers Cancel / Local only / Local + Repo when incident was pushed
- Add Mistral as AI provider (OpenAI-compat, api.mistral.ai/v1,
  mistral-small-latest default)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/new.tsx

@@ -10,6 +10,7 @@ import {
   Alert,
 } from "react-native";
 import { router, useLocalSearchParams, useNavigation } from "expo-router";
+import { useSafeAreaInsets } from "react-native-safe-area-context";
 import * as SecureStore from "expo-secure-store";
 import {
   createIncident,
@@ -55,6 +56,7 @@ type VoiceField = "title" | "service" | "symptom" | "rootCause" | "fix";
 export default function NewIncidentScreen() {
   const { editId } = useLocalSearchParams<{ editId?: string }>();
   const navigation = useNavigation();
+  const insets = useSafeAreaInsets();
 
   const [form, setForm] = useState<IncidentDraft>({
     title: "",
@@ -250,7 +252,7 @@ export default function NewIncidentScreen() {
       behavior={Platform.OS === "ios" ? "padding" : undefined}
     >
       <ScrollView
-        contentContainerStyle={{ padding: 16, paddingBottom: 32 }}
+        contentContainerStyle={{ padding: 16, paddingBottom: 32 + insets.bottom }}
         keyboardShouldPersistTaps="handled"
       >
         {labelRow("Title *", "title")}