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/index.tsx

@@ -8,6 +8,7 @@ import {
   Alert,
 } from "react-native";
 import { router, useFocusEffect } from "expo-router";
+import { useSafeAreaInsets } from "react-native-safe-area-context";
 import * as SecureStore from "expo-secure-store";
 import { getIncidents, markIncidentPushed } from "@/lib/db";
 import { pushIncidentToGit, loadGitConfig } from "@/lib/git";
@@ -132,6 +133,7 @@ export default function HomeScreen() {
   }
 
   const gitConfigured = gitConfig !== null;
+  const insets = useSafeAreaInsets();
 
   return (
     <View style={{ flex: 1, backgroundColor: Colors.bg }}>
@@ -141,7 +143,7 @@ export default function HomeScreen() {
         <FlatList
           data={incidents}
           keyExtractor={(item) => item.id}
-          contentContainerStyle={{ padding: 16, paddingBottom: 96 }}
+          contentContainerStyle={{ padding: 16, paddingBottom: 96 + insets.bottom }}
           ListEmptyComponent={
             <Text
               style={{
@@ -275,7 +277,7 @@ export default function HomeScreen() {
           onPress={() => router.push("/new")}
           style={{
             position: "absolute",
-            bottom: 24,
+            bottom: 24 + insets.bottom,
             right: 24,
             width: 56,
             height: 56,
@@ -302,6 +304,7 @@ export default function HomeScreen() {
             borderTopWidth: 1,
             borderTopColor: Colors.border,
             padding: 12,
+            paddingBottom: 12 + insets.bottom,
             gap: 10,
           }}
         >