LLM Oneshot Prompts, Oneshotted Apps, and Cursor Rules (C#/Rust/TS)

[bradleyshep]

Description of Changes

This PR introduces an LLM One-Shot App Generation benchmarking framework and comprehensive Cursor rules for SpacetimeDB development.

Cursor Rules (docs/.cursor/rules/):

• spacetimedb.mdc - General SpacetimeDB concepts and architecture
• spacetimedb-csharp.mdc - C# module and client patterns
• spacetimedb-rust.mdc - Rust module development
• spacetimedb-typescript.mdc - TypeScript SDK usage

LLM One-Shot Framework (tools/llm-oneshot/):

• Benchmarking tool to measure how well AI can one-shot SpacetimeDB apps
• Composable prompt system with 12 cumulative feature levels (basic chat → full-featured with threading, permissions, presence, etc.)
• Support for 4 tech stacks: TypeScript+SpacetimeDB, TypeScript+PostgreSQL, Rust+SpacetimeDB, C#+SpacetimeDB
• Additional Cursor rules for deployment, grading, and frontend patterns

Sample One-Shotted Apps:

• Multiple chat-app implementations (TypeScript, Rust, C#/MAUI)
• Multiple paint-app implementations (TypeScript, Rust, C#/MAUI)

API and ABI breaking changes

None - this is a documentation and tooling addition only.

Expected complexity level and risk

1 - Trivial addition of documentation, tooling, and example applications. No changes to core SpacetimeDB functionality. The tools/llm-oneshot/ folder is entirely self-contained and the Cursor rules in docs/ are purely informational.

Testing

• Verified Cursor rules load correctly in IDE
• Ran one-shot generation with various prompt levels to validate rules work
• Sample apps compile and deploy correctly

[github-advanced-security]

CodeQL found more than 20 potential problems in the proposed changes. Check the Files changed tab for more details.