Split test-examples into two phases: build all examples in parallel
first, then run tests serially against pre-built binaries. Abort on any
build failure instead of skipping tests for that example.

Replace the centralized `examples/test-examples.toml` with individual
`test.toml` files in each example directory, updating the test runner
and related documentation accordingly.

Refactor program configuration types into a dedicated public `config`
module under `mingling_core`, making `StructuralRendererSetting`
accessible via `mingling_core::config` instead of the crate root.

Update all internal references and setup modules to use the new
`config::` path convention.

Replace the `with_dispatchers` tuple syntax with chained
`with_dispatcher` calls to match the current API and remove
the obsolete section about tuple-based registration.

Add breaking change for `with_dispatcher` removal, renumber feature
items, and outline automated `dispatcher_tree` optimization plan.

Replace the separate code/docs CI jobs and local check flags with
a unified `--check-*` flag system, enabling each check to run
independently across a platform matrix.