chore: import upstream snapshot with attribution

testdata/ssh/Dockerfile

@@ -0,0 +1,36 @@
+FROM alpine:3.21
+RUN apk add --no-cache openssh-server tar && \
+    ssh-keygen -A && \
+    adduser -D -s /bin/sh testuser && \
+    passwd -u testuser && \
+    mkdir -p /home/testuser/.ssh && \
+    ssh-keygen -t ed25519 -f /home/testuser/.ssh/id_test -N "" && \
+    cat /home/testuser/.ssh/id_test.pub \
+        >> /home/testuser/.ssh/authorized_keys && \
+    chmod 700 /home/testuser/.ssh && \
+    chmod 600 /home/testuser/.ssh/authorized_keys && \
+    chown -R testuser:testuser /home/testuser/.ssh && \
+    cp /home/testuser/.ssh/id_test /tmp/test_ssh_key && \
+    chmod 644 /tmp/test_ssh_key
+# Configure sshd: enable pubkey auth explicitly and allow
+# login for testuser. Write a fresh config to avoid any
+# Alpine defaults that might interfere.
+RUN printf '%s\n' \
+    "Port 22" \
+    "PubkeyAuthentication yes" \
+    "AuthorizedKeysFile .ssh/authorized_keys" \
+    "PasswordAuthentication no" \
+    "PermitRootLogin no" \
+    "Subsystem sftp /usr/lib/ssh/sftp-server" \
+    > /etc/ssh/sshd_config
+
+# Claude session fixture: file must be <project>/<uuid>.jsonl
+# (DiscoverClaudeProjects looks for .jsonl files directly in
+# project dirs, not inside subdirectories)
+RUN mkdir -p /home/testuser/.claude/projects/test-project
+COPY testdata/ssh/session.jsonl \
+    /home/testuser/.claude/projects/test-project/aaaaaaaa-1111-2222-3333-444444444444.jsonl
+RUN chown -R testuser:testuser /home/testuser/.claude
+
+EXPOSE 22
+CMD ["/usr/sbin/sshd", "-D", "-e"]