docs(binding): document widened capability matrix

[jmgilman]

Summary

• document required and optional scalar input forms and canonical omission semantics
• document nested structs, lists, maps, pointers, numeric constraints, byte sequences, and nil/omitempty output behavior
• preserve the flat discovery field schema while defining deterministic compact nested type notation
• add the request-scoped 8 MiB MaxIntermediateValueBytes contract and its relationship to MaxValueBytes
• correct the worker-bind, parent-rebind/canonicalize, authorize, dispatch, and output-conversion boundary descriptions

Completes the implementation series for #23.

Failure contracts

• unsupported reflected type graphs fail registration
• invalid returned numeric values project capability failure
• depth, per-value byte, and aggregate native-result byte exhaustion project resource limit

Validation

• moon run docs:build --force
• GitHub Markdown API render check for pipe-bearing type-notation table cells
• git diff --check origin/master

Review

The persistent bounded reviewer verified the type universe, null and omitempty behavior, notation examples, aggregate accounting, failure projection, boundary ordering, unchanged flat schema and three-tool surface, and documentation fit. One GitHub table-rendering issue was fixed and re-reviewed.