feat(profiles): seal builtin import provenance and expose read-only editor imports

Retain the evaluated JSON launch entrypoint, seal observed builtin source bytes and digests as verified provenance, and fail on missing/corrupt dependencies without Runtime builtin reevaluation. Cover real HTTP commits and launch resolution, including worker mode and Workspace Config feature composition.

Expose read-only builtin import completions/diagnostics in the editor and rebuild wasm32 release assets with wasm-bindgen 0.2.117. Document public paths, ordinary composition, limits, resave semantics, and the lazy-cycle incident.

Validation: worker-runtime 344 library + 34 integration tests; workspace-server 609 library + 11 binary tests plus final builtin HTTP/launch tests (2); archive tests (16); native WASM tests (2); real-WASM/web tests (37), editor component tests (10); root cargo check, cargo fmt --all -- --check and git diff --check HEAD pass.

web/workspace/test/config-source/toolchain.test.ts

@@ -89,6 +89,31 @@ Deno.test("completion starts only after non-whitespace typing", () => {
   );
 });
 
+Deno.test("toolchain preserves read-only builtin import completion detail", () => {
+  const result = toCodeMirrorCompletion({
+    from: 8,
+    items: [{
+      label: "$builtin/profiles/companion.dcdl",
+      kind: "file",
+      detail: "read-only builtin Decodal source",
+      priority: 0,
+    }],
+  });
+  assert(result !== null, "builtin completion should be available");
+  assert(
+    result.options[0].label === "$builtin/profiles/companion.dcdl",
+    "builtin namespace must not become a workspace path",
+  );
+  assert(
+    result.options[0].detail === "read-only builtin Decodal source",
+    "CodeMirror must display the read-only completion detail",
+  );
+  assert(
+    result.options[0].type === "file",
+    "builtin imports remain file completions",
+  );
+});
+
 Deno.test("toolchain preserves WASM UTF-16 completion ranges for CodeMirror", () => {
   const result = toCodeMirrorCompletion({
     from: "let 名 = ".length,