chore: add .env.example, gitignore .env.local

.env.example

@@ -0,0 +1,9 @@
+# Copy to .env.local and fill in real values
+# These are never committed — .env.local is gitignored
+
+# Sentry DSN (https://sentry.io → Project → Settings → Client Keys)
+VITE_SENTRY_DSN=
+
+# PostHog (https://posthog.com → Project → Settings → Project API Key)
+VITE_POSTHOG_KEY=
+VITE_POSTHOG_HOST=https://eu.i.posthog.com

.gitignore

@@ -67,3 +67,7 @@ CODE-HEALTH-REPORT.md
 # Tauri signing keys (never commit private keys)
 *.key
 *.key.pub
+
+# Local environment variables (never commit)
+.env.local
+.env.*.local