fix: diagnose nested partial Profile values in the editor (T-710)

Resolve MR sequence 3 profile_nested_editor_diagnostics_missing with a separate, non-materializing authoring constraint pass. Preserve omission and the persisted evaluation schema, and map nested/imported failures to supplied virtual-source spans. Exercise actual Backend schema in native and regenerated WASM tests for empty/partial values, worker and feature types, unknown fields, imports and composition.

Validation: root cargo check; config-source 38; config-source-wasm native/doc; unfiltered yoi-workspace-server 642 lib + 11 bin; worker-runtime 340 lib + 17 per binary; server-api --features typescript 77; focused Deno 39; deno task check; wasm32 release build, wasm-bindgen 0.2.117 + Binaryen 132 -Oz regeneration; cargo fmt/diff checks. Earlier checker failure did not recur: Reviewer independently passed full source suite and exact original baseline checker filter, recorded in MR sequence 3.

resources/config-schema/profile-authoring.dcdl

@@ -1,5 +1,6 @@
-# Completion-only shape of partial Profile values. This is never materialized or
-# used as defaults: omitted fields remain omitted until Manifest resolution.
+# Editor-only shape of partial Profile values, used for completion and constraint
+# analysis without materialization. Never used as defaults: omitted fields remain
+# omitted until Manifest resolution.
 let
     Flag = { enabled = Bool; };
     Model = {