v0.88.0 - sessions, binary websockets & templating ergonomics

Highlights

• First-party sessions — signed-cookie sessions via request.session (#945, #1411)
• Binary WebSocket frames — binary frames are forwarded to your message handler (#1148, #1416)
• render() templating shortcut — render a local templates/ folder without constructing JinjaTemplate by hand; engine-agnostic with Jinja2 as the default (#1223, #1418)
• Hot reload fixed for module launches — python -m ... now relaunches correctly on file changes (#654, #1417)
• Batch of quick-win fixes (#1415) — resolves #1099, #1147, #1273, #495, #470, #1192
• Docs — single-page cheatsheet (#1062, #1414) and a bilingual (EN/ZH) templating refresh
• CI — lint no longer builds the Rust extension (#1413)

Full Changelog: v0.87.0...v0.88.0