fix: Use Docker Hub base image instead of GHCR (auth issues)

ghcr.io/astral-sh/uv requires authentication which fails on
HyperShift clusters without GHCR pull secrets. Switch to
python:3.12-slim-bookworm (Docker Hub, no auth needed) and
install uv via pip.

Affects: weather_service, weather_tool (E2E test agents)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Ladislav Smola <lsmola@redhat.com>

Author: Ladas

a2a/weather_service/Dockerfile

@@ -1,6 +1,9 @@
-FROM ghcr.io/astral-sh/uv:python3.12-bookworm-slim
+FROM python:3.12-slim-bookworm
 ARG RELEASE_VERSION="main"
 
+# Install uv
+RUN pip install --no-cache-dir uv
+
 WORKDIR /app
 COPY . .
 RUN uv sync --no-cache --locked --link-mode copy

mcp/weather_tool/Dockerfile

@@ -1,6 +1,9 @@
-FROM ghcr.io/astral-sh/uv:python3.12-bookworm-slim
+FROM python:3.12-slim-bookworm
 ARG RELEASE_VERSION="main"
 
+# Install uv
+RUN pip install --no-cache-dir uv
+
 WORKDIR /app
 COPY . .
 RUN uv sync --no-cache --locked --link-mode copy