fix: initialize ChromaDB collection in Dockerfile

Dockerfile

@@ -3,6 +3,7 @@ WORKDIR /app
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 ENV USER_AGENT="outreach-composer-for-job-search"
+RUN python -c "import chromadb; chromadb.Client().get_or_create_collection('my_collection')._embed('sample text')"
 COPY . .
 EXPOSE 8501
 CMD ["streamlit", "run", "app.py"]