Replace raw dictionary casting with ScriptParameters wrapper that provides
Get<T>, Get<T?>, Get<T[]>, and Get<List<T>> with clear error messages,
numeric conversion, and JsonElement support for Inbound API parameters.
Organize documentation by moving requirements (HighLevelReqs, Component-*,
lmxproxy_protocol) to docs/requirements/ and test infrastructure docs to
docs/test_infra/. Updates all cross-references in README, CLAUDE.md,
infra/README, component docs, and 23 plan files.