Document Clear Street brokerage

[AlexCatarino]

Summary

Adds the Clear Street brokerage documentation, placed after Charles Schwab:

• 01 Cloud Platform/10 Live Trading/02 Brokerages/08 ClearStreet: account types and API key steps, asset classes, data providers, orders, rate limit, fees, margin, slippage, fills, settlements, security, deposits, demo algorithm, deploy steps, and troubleshooting.
• 03 Writing Algorithms/24 Reality Modeling/05 Brokerages/02 Supported Models/08 ClearStreet: the ClearStreetBrokerageModel pages.
• 05 Lean CLI/09 Live Trading/01 Brokerages/08 ClearStreet: cloud and local deployment with --clearstreet-access-token and --clearstreet-account-id.
• Shared partials in Resources/brokerages/clearstreet, the introduction and create-credentials snippets.
• Renumbers Webull and the following brokerages in the three sections and their 00.json files.
• Adds ClearStreetBrokerageSettings to the API yaml and the Create Live Algorithm request page, the CLI wizard lists, and the Supported Brokerages table.

Facts come from Lean.Brokerages.ClearStreet, LEAN's ClearStreetBrokerageModel / ClearStreetOrderProperties, lean-cli PR #666, and the Clear Street API docs.

Notes:

• LEAN has no ClearStreetFeeModel, so the Fees page documents the DefaultBrokerageModel fallback (Interactive Brokers fee model for Equity and Equity Options, zero fees for Index Options). No Transaction Fees model page was added.
• The order-type table follows ClearStreetBrokerageModel, which rejects market-on-open and market-on-close orders even though clearstreet.json lists them.
• Clear Street serves no market data, so the pages point to the QuantConnect data provider and there is no CLI Data Provider page.

Test plan

• python -c "import yaml; yaml.safe_load(open('QuantConnect-Platform-2.0.0.yaml', encoding='utf-8'))" passes.
• Every DOCS_RESOURCES include on the new pages resolves to an existing file.
• python url_check.py reports no errors on the new pages; the 3 remaining errors are pre-existing on unrelated pages.
• The three renumbered sections are contiguous and match their 00.json keys.
• Render the new pages on the docs site and check the Clear Street entries in the brokerage landing pages.