Fix Dockerfile: use flat app/ structure, remove backend/ paths

Dockerfile

@@ -1,6 +1,7 @@
 # ============================================================
-# AuthorBot RAG API — Root Dockerfile for HuggingFace Spaces
-# Routing: /ui (Gradio) · /widget · /admin · /api/v1 · /health
+# AuthorBot RAG API — HuggingFace Spaces Dockerfile
+# Entry: app.py → app/main.py (FastAPI)
+# Routes: /api/chat/{slug} · /api/admin/{slug} · /api/super · /health
 # ============================================================
 FROM python:3.11-slim AS builder
 
@@ -14,7 +15,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 WORKDIR /app
 
-COPY backend/requirements.txt .
+COPY requirements.txt .
 RUN pip install --no-cache-dir --upgrade pip && \
     pip install --no-cache-dir -r requirements.txt
 
@@ -39,15 +40,19 @@ ENV UPLOAD_STORAGE_PATH=/data/uploads
 COPY --from=builder /usr/local/lib/python3.11/site-packages /usr/local/lib/python3.11/site-packages
 COPY --from=builder /usr/local/bin /usr/local/bin
 
-COPY backend /app
+# Copy entire flat project (app/, static/, app.py, requirements.txt)
+COPY app/ ./app/
+COPY static/ ./static/
+COPY app.py .
 
-RUN mkdir -p /app/logs /data/chroma /data/uploads /data/redis && \
+RUN mkdir -p /data/chroma /data/uploads /data/sessions /data/redis && \
     printf 'dir /data/redis\nbind 127.0.0.1\nport 6379\ndaemonize yes\nlogfile /dev/null\n' > /app/redis-hf.conf
 
 RUN adduser --disabled-password --gecos "" --uid 1000 appuser && \
     chown -R appuser:appuser /app /data
 USER appuser
 
+# Pre-warm ML models (non-fatal if network unavailable at build time)
 RUN python -c "from sentence_transformers import CrossEncoder; CrossEncoder('cross-encoder/ms-marco-MiniLM-L-6-v2')" || true
 RUN python -c "from sentence_transformers import SentenceTransformer; SentenceTransformer('sentence-transformers/all-MiniLM-L6-v2')" || true
 
@@ -58,4 +63,4 @@ HEALTHCHECK --interval=30s --timeout=10s --start-period=180s --retries=5 \
 
 EXPOSE 7860
 
-CMD ["sh", "-c", "mkdir -p /data/chroma /data/uploads /data/redis && redis-server /app/redis-hf.conf && sleep 1 && alembic upgrade head && uvicorn app.main:app --host 0.0.0.0 --port 7860 --workers 1 --loop uvloop --http httptools"]
+CMD ["sh", "-c", "mkdir -p /data/chroma /data/uploads /data/sessions /data/redis && redis-server /app/redis-hf.conf && sleep 1 && uvicorn app.main:app --host 0.0.0.0 --port 7860 --workers 1 --loop uvloop --http httptools"]