refactor: Use package knowledge in package integrations (#13460)
### Description
Part 5 of the package/scope knowledge completion stack.
Move boundaries, microfrontend discovery, and `get-mfe-port` package
ownership onto authoritative scopes. Nested package lookup uses the
deepest directory owner, native/aggregate scopes are handled explicitly,
and dependency tables remain later-phase payloads.
### Testing Instructions
- `cargo test -p turborepo-boundaries`
- `cargo test -p turborepo-lib --lib microfrontends::test`
- `cargo test -p turborepo-lib --lib commands::get_mfe_port::tests`
