feat: migrate protocol and HTTP to structured interface references

T-20: identify interfaces by exact scope/name pairs; add optional opaque scope_ref metadata and separate shape validation from path-dependent scope compatibility. Preserve call error precedence, strict JSON, validators and transport boundaries. Mechanically migrate consumers and document API/wire compatibility and deferred lifecycle semantics.

Validation: cargo fmt --all --check; git diff --check; cargo check --workspace --all-targets; cargo test -p wip-protocol -p wip-http; cargo test --workspace (221 passing tests including doctests); cargo test --workspace --all-targets; nix develop --command cargo clippy --workspace --all-targets -- -D warnings; RUSTDOCFLAGS="-D warnings" cargo doc --workspace --no-deps. All pass. cargo/rustc 1.95.0; development-shell Clippy/rustc 1.97.1.

CHANGELOG.md

@@ -2,6 +2,15 @@
 
 All notable changes to the published WIP Rust crates are documented here.
 
+## Unreleased
+
+- Breaking Protocol/HTTP migration from opaque Interface reference strings to
+  exact `(scope, name)` records in Objects, fetches and calls, with optional
+  opaque `scope_ref` metadata. Adds shape and placement-aware scope validation
+  without changing routes, validators or the wire error-code set.
+- Mechanically migrates workspace consumers and fixtures. See [MIGRATION.md](MIGRATION.md)
+  for API/wire examples and the deferred Host/Client lifecycle semantics.
+
 ## 0.1.0
 
 Initial public release of: