feat(qizheng): vendor stem-branch and expose three read-only chart APIs

Add Apache-2.0 @4n6h4x0r/stem-branch 0.8.0, a seven-governors adapter,
and POST /api/qizheng, /api/western, /api/ephemeris_events.

BUG-700 remains blocked (do not call --pillars). BUG-701 and BUG-702 are
resolved. BUG-703 is investigating (panchanga Lahiri). Skill is not bumped.

deploy/gated-paths.txt

@@ -26,6 +26,7 @@ references/**
 skills/**
 deploy/**
 frontend/**
+vendor/**
 #
 # Repository files read by frontend/tests at gate time
 contracts/**

deploy/railway-api.Dockerfile

@@ -9,7 +9,7 @@ WORKDIR /app
 COPY requirements.txt ./
 RUN sed -i 's|http://deb.debian.org|https://mirrors.aliyun.com|g' /etc/apt/sources.list.d/debian.sources \
     && apt-get -o Acquire::Retries=3 -o Acquire::http::Timeout=30 -o Acquire::https::Timeout=30 update \
-    && apt-get install -y --no-install-recommends build-essential \
+    && apt-get install -y --no-install-recommends build-essential nodejs \
     && python -m pip install -r requirements.txt \
     && apt-get purge -y --auto-remove build-essential \
     && rm -rf /var/lib/apt/lists/*
@@ -20,5 +20,6 @@ COPY jyotish_vedic ./jyotish_vedic
 COPY references ./references
 COPY scripts ./scripts
 COPY skills ./skills
+COPY vendor ./vendor
 
 CMD ["sh", "-c", "exec python scripts/jyotish_api_server.py --host 0.0.0.0 --port \"${PORT:-5200}\""]