mcpp 0.0.3 inferred-defaults catch up with what we'd been spelling
out by hand:
- `[language]` section is gone — `[package].standard` (default `c++23`)
  + `[build]` knobs cover the same ground.
- `[modules].sources` defaults to `src/**/*.{cppm,cpp,cc,c}` and
  `[modules].exports` is no longer consulted (the modgraph derives
  exports from the actual `export module` declarations).

The dependency block stays the same — mbedtls is still a public
runtime dep — but the comment now points at 0.0.3's transitive
walker as the reason downstream consumers (e.g. mcpplibs.llmapi)
don't need to repeat it.