Fix Dockerfile: GID 1001, remove genhtml (included in lcov), cleanup test file

Entire-Checkpoint: 0d9a8cfb0768

ci/Dockerfile.ci

@@ -2,9 +2,9 @@ FROM ubuntu:26.04
 
 ENV DEBIAN_FRONTEND=noninteractive
 
-# Create jenkins user with same UID as host jenkins (typically 1000)
-RUN groupadd -g 1000 jenkins && \
-    useradd -u 1000 -g 1000 -m -s /bin/bash jenkins
+# Create jenkins user (UID 1001 to avoid conflicts with existing users)
+RUN groupadd -g 1001 jenkins && \
+    useradd -u 1001 -g 1001 -m -s /bin/bash jenkins
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
@@ -23,8 +23,7 @@ RUN apt-get update && \
       qt6-base-dev-tools \
       qt6-tools-dev \
       qt6-tools-dev-tools \
-      lcov \
-      genhtml && \
+      lcov && \
     rm -rf /var/lib/apt/lists/*
 
 # Set Qt platform for headless testing