deet: Type-safe relational programming system

WHAT: A typed, versioned, testable relational programming system. 
Source-of-truth is a dependency graph (DAG) of relational expressions.

CORE CONCEPTS:
- Relation: Table-like value with schema (columns, types, nullability)
- Node: Operator application producing a relation
- DAG: Directed Acyclic Graph of dependent nodes
- Model: Named node for consumption
- Lens: UI/editor projection (grid, code, SQL)

LANGUAGE (.dt):
- DSL for defining data transformations
- Pipeline operator |> for composing operations
- Built-in type system with nullability tracking
- Sources, models, macros, tests

CLI COMMANDS:
- deet init     - Create new project
- deet check    - Typecheck and lint
- deet compile  - Compile to target backend
- deet test     - Run tests
- deet deploy   - Deploy to production

BACKENDS:
- DuckDB (local development)
- PostgreSQL
- BigQuery
- Snowflake

FILE STRUCTURE:
- src/          - .dt source files
- tests/        - Test files
- dist/         - Compiled artifacts
- rxg.toml      - Package config
- rxg.lock      - Dependency lockfile

GETTING HELP:
- /llms-full.txt - Comprehensive documentation
- /docs          - Interactive docs
- GitHub issues  - Bug reports
- Discord        - Community chat

STATUS: v0.8.0 (feature complete)
Next: v1.0.0 production release