chore: add workspace clippy lints, release profiles, COMPAT.md, diff-registry.sh

- Workspace clippy lints: or_fun_call, redundant_clone, collection_is_never_read,
  naive_bytecount, stable_sort_primitive, large_types_passed_by_value, assigning_clones
- Fix or_fun_call in cargo_registry.rs (unwrap_or -> unwrap_or_else)
- Release profiles: release (thin LTO) + release-official (full LTO, codegen-units=1)
- COMPAT.md: protocol compatibility matrix for all 7 registries (40 endpoints)
- scripts/diff-registry.sh: differential smoke tests (Docker/npm/Cargo/PyPI/Go/Raw)

nora-registry/Cargo.toml

@@ -64,3 +64,6 @@ http-body-util = "0.1"
 [[bench]]
 name = "parsing"
 harness = false
+
+[lints]
+workspace = true