fix(polymarket): add venv-first setup for py-clob-client skills

[taariq]

Summary

• update Quick Start setup for all four py-clob-client Polymarket skills to use a local virtual environment first
• replace direct pip install -r requirements.txt with:
  • python3 -m venv .venv
  • source .venv/bin/activate
  • python -m pip install --upgrade pip
  • python -m pip install -r requirements.txt
• improve shared live-runtime import error guidance to point users to venv-first dependency install

Affected Skills

• polymarket/maker-rebate-bot
• polymarket/high-throughput-paired-basis-maker
• polymarket/paired-market-basis-maker
• polymarket/liquidity-paired-basis-maker

Validation

• python3 -m compileall polymarket/_shared/polymarket_live.py
• python3 -m pytest polymarket/maker-rebate-bot/tests polymarket/high-throughput-paired-basis-maker/tests polymarket/paired-market-basis-maker/tests polymarket/liquidity-paired-basis-maker/tests (fails in this environment because pytest is not installed)

Closes #78