Quickstart remix

[bradleyshep]

Based on #4112

Description of Changes

Adds a Remix quickstart template and documentation for SpacetimeDB.

Template (templates/remix-ts/)

• SpacetimeDB module with TypeScript (spacetimedb/src/index.ts)
• Remix app with Vite configuration
• SpacetimeDB provider in app/providers.tsx with proper SSR/hydration handling
• Example route (app/routes/_index.tsx) demonstrating useTable and useReducer hooks
• Pre-generated module bindings in src/module_bindings/

Documentation (docs/docs/00100-intro/00200-quickstarts/00175-remix.md)

• Step-by-step quickstart guide following existing pattern
• Covers project creation with spacetime dev --template remix-ts
• Explains project structure, provider pattern, and React hooks usage
• Documents environment variable configuration (VITE_SPACETIMEDB_HOST, VITE_SPACETIMEDB_DB_NAME)

Consistency

• Environment variables follow the same HOST/DB_NAME naming convention as other quickstarts
• Documentation structure mirrors Next.js and React quickstarts
• Dev server runs on port 3001 to avoid conflict with SpacetimeDB on port 3000

API and ABI breaking changes

None.

Expected complexity level and risk

1 - Additive change only. New template and documentation, no modifications to existing functionality.

Testing

• Run spacetime dev --template remix-ts my-remix-app and verify app starts
• Verify SpacetimeDB connection works at http://localhost:3001
• Test adding a person via the UI form
• Verify SSR doesn't crash (SpacetimeDB provider defers to client-side)
• Check documentation renders correctly in Docusaurus