test(melo): add Dockerfile and document native-build failures

User hit "Failed building wheel for tokenizers / fugashi / mecab-python3"
on first install. Root cause is missing prebuilt wheels (typically
Python 3.12+) and missing MeCab/Rust system tools.

- Dockerfile: python:3.11-slim + MeCab + Rust, one-shot path that
  bypasses host setup entirely.
- README: explicit "Python 3.10/3.11 OR Docker" guidance, per-error
  troubleshooting, OS-specific system-package commands.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

melo-test/Dockerfile

@@ -0,0 +1,35 @@
+# MeloTTS-Korean 테스트 서버 컨테이너.
+# 호스트에 Python/MeCab/Rust 안 깔고 싶을 때 사용.
+#
+# 빌드:  docker build -t melo-test .
+# 실행:  docker run --rm -p 7860:7860 melo-test
+#        (가중치 캐시 유지하려면: -v melo-cache:/root/.cache/huggingface)
+FROM python:3.11-slim
+
+# fugashi/mecab-python3 빌드용 MeCab + tokenizers 빌드용 Rust + 기본 빌드 툴
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        build-essential \
+        git \
+        curl \
+        ca-certificates \
+        mecab \
+        libmecab-dev \
+        mecab-ipadic-utf8 \
+    && rm -rf /var/lib/apt/lists/*
+
+# Rust (tokenizers 소스 빌드 fallback 대비)
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \
+    | sh -s -- -y --default-toolchain stable --profile minimal
+ENV PATH="/root/.cargo/bin:${PATH}"
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install --upgrade pip setuptools wheel \
+    && pip install -r requirements.txt
+
+COPY . .
+
+EXPOSE 7860
+ENV PORT=7860
+CMD ["python", "server.py"]