Initial scaffold: Flask webui + APScheduler + Playwright automation for MassPrice rule scheduling

Drives massprice.tcgplayer.com's Run Rule action per-rule on a
user-configured schedule (multiple times/day, day-of-week toggles),
replacing MassPrice's native scheduler (capped at 15 schedules
account-wide, one run/day, with observed clock drift). Deployed via
Forgejo push-to-deploy on Unraid, matching arr-summary/card-grader.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H6TgffxTvYhqxykAbVQg2v

Dockerfile

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+FROM mcr.microsoft.com/playwright/python:v1.47.0-jammy
+
+LABEL net.unraid.docker.webui="http://[IP]:[PORT:5000]/"
+LABEL maintainer="MassPrice Scheduler"
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY . .
+
+EXPOSE 5000
+
+CMD ["gunicorn", "--config=gunicorn.conf.py", "app:app"]