Instrument and improve incremental workspace checks

Profile source capture, Nix evaluation/realization, resource/query checking,
and implementation builds without putting timings into immutable outputs.
Keep modular repositories; bound independent capture work, snapshot jj once
per observation, and retain final concurrent-edit and Git completeness checks.

Compose exact resource/closure/frontend/toolchain checks as memoized Nix
derivations. Preserve whole-workspace validation and the full compiler path
when no checked dependency is supplied. Share canonical Nixpkgs by content,
index workspace build contexts once, and narrow lock/driver/compiler inputs
with conservative complete-source fallback. Batch React witness checks only
when distinct source closures cannot share ambient declarations; otherwise
run the original independent TypeScript checks.

Seed local authoring toolchains with exact canonical fetch identities when
they match the selected inputs; retain store-path inputs for overrides.
Add generic correctness checks rather than permanent Reader timing/content
fixtures. Verify actual Reader edits and rejection/recovery in a private
workbench, preserving the original user's workbench and runtime.

Query checking currently caches at resource/closure boundaries, not individual
query semantic dependency boundaries. Template helper pins and reproducible
fixture snapshots follow in a separate publication change.

assemble-package.nix

@@ -4,7 +4,12 @@
   artifacts,
 }:
 let
+  buildTools = import ./build-tools.nix;
   groups = map (artifact: artifact.caminoGroup or artifact) artifacts;
+  compiler = builtins.path {
+    path = "${context.generator}/libexec/quixos-protocol/execution-world.mjs";
+    name = "execution-world.mjs";
+  };
   config = pkgs.writeText "camino-package-assembly.json" (
     builtins.toJSON {
       inherit groups;
@@ -14,7 +19,7 @@ let
         packageRevisionId
         sharedRuntime
         ;
-      compiler = "${context.generator}/libexec/quixos-protocol/execution-world.mjs";
+      inherit compiler;
       node = "${pkgs.nodejs_24}/bin/node";
       esbuild = "${pkgs.esbuild}/bin/esbuild";
       shell = "${pkgs.runtimeShell}";
@@ -30,5 +35,5 @@ pkgs.runCommand "camino-package"
     };
   }
   ''
-    ${pkgs.nodejs_24}/bin/node ${./.}/assemble-package.mjs ${config}
+    ${pkgs.nodejs_24}/bin/node ${buildTools}/assemble-package.mjs ${config}
   ''