Make workspace authoring converge through immutable Nix candidates

Coordinate registered resource edits bottom-up into retained exact remote sources.
Use one Nix-owned source graph for provisional checking, template publication,
explicit baseline upgrades and host activation; retain independent runtime pins.

Add scoped contract inspection, historical recovery, derived worklists, crash-safe
locks, named dependency adoption and plain-QX structural editing. Repair TODO
ownership and template instantiation, and document the supported agent workflow.

Validated with protocol and command suites, real jj/Nix convergence and cache
checks, TS/React installed-command acceptance, and fresh TODO first-edit acceptance.
No live deployment or public publication performed. Props projection generation
and a one-command rich feature generator remain explicitly outside this delivery.

test/scaffold-recipes.test.ts

@@ -55,4 +55,8 @@ test("package/function/migration scaffolds register implementations and refresh
     await execFile("nix-instantiate", ["--parse", path.join(packageRoot, "flake.nix")]);
   }
   await assert.rejects(() => apply("function", {...base, name: "play", id: "export:play"}), /unique/);
+  await assert.rejects(() => planStructure(root, {kind: "package", source, resourceRoot: base.directory, validation: "syntax", files: [{
+    file: `${base.directory}/package.qx`, edits: [{operation: "replace", target: {kind: "packageResourceDecl", id: "package:chess"},
+      source: 'package Other id "package:other" revision "package:other@1" {}'}],
+  }]}), /scaffold-owned package identity/);
 });