feat: typed module system (V1-V5)

[darinkishore]

Summary

• Typed module system: Module trait with associated Input/Output types, Predict<S> returns Predicted<O> with Deref<Target=O> for direct field access and .metadata() for call details
• Library modules: ChainOfThought<S> (adds reasoning field), ReAct<S> (tool-calling loop), ModuleExt combinators (.map(), .and_then())
• Optimizer interface: TypedMetric, COPRO/MIPROv2/GEPA all work through optimizer.compile(&mut module, trainset, &metric) with Facet-based predictor discovery
• Typed data loading: DataLoader::load_csv::<S>() returns Vec<Example<S>> directly, with load_csv_with for custom column mapping
• V6 dynamic graph deferred: Runtime code removed, scoped to V1-V5 typed-only path
• Docs cleanup: Purged 29 AI execution artifact files from docs/plans/, fixed all stale API references (call_with_meta, forward_with_config, #[Signature(cot)], example!/prediction! macros), rewrote introduction, predictors, and module pages to match current typed API

Test plan

• cargo check passes (2 minor dead-code warnings, pre-existing)
• cargo test passes
• Spot-check docs render on mintlify preview
• Run examples (cargo run --example 01-simple, cargo run --example 08-optimize-mipro)

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