docs: add example environment configuration file

.env.example

@@ -0,0 +1,25 @@
+# === ImmichFrame Configuration ===
+
+# REQUIRED
+IMMICH_URL=http://your-immich-server:2283
+IMMICH_API_KEY=your-api-key-here
+
+# Slideshow
+SLIDESHOW_INTERVAL=30
+TRANSITION_DURATION=2
+IMAGE_FIT=contain
+SHUFFLE=true
+BACKGROUND_BLUR=true
+
+# Overlays
+SHOW_CLOCK=true
+SHOW_DATE=true
+SHOW_EXIF=true
+SHOW_PROGRESS=true
+
+# Auto-start (optional)
+# ALBUM_ID=
+# SHOW_FAVORITES_ONLY=false
+
+# Server
+PORT=3000