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>

lib/ai.ts

@@ -3,6 +3,7 @@ import * as SecureStore from "expo-secure-store";
 export type AIProvider =
   | "anthropic"
   | "openai"
+  | "mistral"
   | "perplexity"
   | "ollama"
   | "openrouter"
@@ -18,6 +19,7 @@ const KEYS = {
 export const AI_PROVIDER_BASE_URLS: Record<AIProvider, string> = {
   anthropic: "https://api.anthropic.com",
   openai: "https://api.openai.com/v1",
+  mistral: "https://api.mistral.ai/v1",
   perplexity: "https://api.perplexity.ai",
   ollama: "http://localhost:11434/v1",
   openrouter: "https://openrouter.ai/api/v1",
@@ -27,6 +29,7 @@ export const AI_PROVIDER_BASE_URLS: Record<AIProvider, string> = {
 export const AI_PROVIDER_MODEL_PLACEHOLDERS: Record<AIProvider, string> = {
   anthropic: "claude-haiku-4-5-20251001",
   openai: "gpt-4o-mini",
+  mistral: "mistral-small-latest",
   perplexity: "llama-3.1-sonar-small-128k-online",
   ollama: "llama3.2",
   openrouter: "openai/gpt-4o-mini",