Simplify README and install instructions

Dockerfile

@@ -1,7 +1,7 @@
 # syntax=docker/dockerfile:1.7
 FROM python:3.11-slim
 
-WORKDIR /image_drop
+WORKDIR /file_drop
 
 ENV PYTHONDONTWRITEBYTECODE=1 \
     PYTHONUNBUFFERED=1
@@ -12,17 +12,12 @@ RUN pip install --no-cache-dir -r requirements.txt \
     && pip install --no-cache-dir python-multipart
 
 # Copy app code
-COPY . /image_drop
-
-
-# Data dir for SQLite (state.db)
-#RUN mkdir -p /data
-#VOLUME ["/data"]
+COPY . /file_drop
 
 # Defaults (can be overridden via compose env)
 ENV HOST=0.0.0.0 \
     PORT=8080 \
-    STATE_DB=/image_drop/data/state.db
+    STATE_DB=/file_drop/data/state.db
 
 EXPOSE 8080