Fix Dockerfile: replace curl-pipe-to-shell with pinned pip install of uv

Co-authored-by: samppanja <21281919+samppanja@users.noreply.github.com>

Author: Copilot

Dockerfile

@@ -6,9 +6,10 @@ WORKDIR /app
 ENV PATH="/root/.local/bin/:$PATH"
 COPY . /app
 
-RUN apt-get update && apt-get install -y curl ca-certificates libmagic1 && curl -LsSf https://astral.sh/uv/install.sh | sh \
-&& apt-get clean && rm -rf /var/lib/apt/lists/* \
-&& uv sync --no-dev --frozen
+RUN apt-get update && apt-get install -y python3-pip ca-certificates libmagic1 \
+    && pip3 install --no-cache-dir --break-system-packages "uv==0.6.3" \
+    && apt-get clean && rm -rf /var/lib/apt/lists/* \
+    && uv sync --no-dev --frozen