Implement a new datalog verification layer using datafrog that:
- Compiles rulespec to datalog on plan_approve
- Extracts facts from action envelope using selectors
- Executes datalog rules on plan_verify
- Writes evaluation results to datalog_evaluation.txt (shadow mode)
Key components:
- crates/g3-core/src/tools/datalog.rs: Full datalog module with:
- compile_rulespec(): Validates and compiles rulespec
- extract_facts(): Extracts facts from envelope YAML
- execute_rules(): Runs datafrog iteration
- 23 comprehensive tests
- crates/g3-core/src/tools/plan.rs:
- execute_plan_approve(): Now compiles rulespec on approval
- shadow_datalog_verify(): Runs datalog and writes to eval file
Results are written to .g3/sessions/<id>/datalog_evaluation.txt
for inspection, NOT injected into context window (shadow mode).
abfac197ab