Install house-style Python deps in the test-pg job too

Why: the job runs the full backend suite against real services; internal/runtime lint tests require python-docx (job 2290: ModuleNotFoundError 'docx') which the plain test job already installs.

Evidence: job 2290 log; all PG/Redis-dependent packages green in the same run (store 2.6s, pgbus, runmgr, ratelimit, server).

Impact: test-pg job setup only.

Refs: Dev PR #325.

.gitea/workflows/ci.yaml

@@ -335,6 +335,8 @@ jobs:
           tar -C /usr/local -xzf "$RUNNER_TEMP/go.tgz"
           ln -sfn /usr/local/go/bin/go /usr/local/bin/go
           ln -sfn /usr/local/go/bin/gofmt /usr/local/bin/gofmt
+      - name: Install house-style Python packages
+        run: python3 -m pip install --break-system-packages -i https://pypi.tuna.tsinghua.edu.cn/simple python-docx python-pptx openpyxl
       - name: Install PostgreSQL, pgvector and Redis
         run: |
           set -euo pipefail