DICS: Staged DI for C# and Unity without runtime reflection

The unusual bits: configuration axes (think: use flags/feature flags for your app) as a first-class concept, almost no runtime reflection, and staged DI - build and validate the whole dependency graph first, instantiate second. Missing deps, cycles, ambiguous bindings, conflicting axis definitions, etc. fail before touching user code.

Most of the implementation was written manually btw. LLM use was limited to docs/tests. The library is battle-tested.