Move package scripts into packages tree

- relocate Bun normalization helpers under `packages/scripts`
- update shared package build logic to use the new paths
- remove obsolete top-level package wrappers

packages/common.nix

@@ -70,8 +70,8 @@ in {
           --no-progress \
 ${renderBunFilters filters}
 
-        bun --bun ${../nix/scripts/canonicalize-node-modules.ts}
-        bun --bun ${../nix/scripts/normalize-bun-binaries.ts}
+        bun --bun ${./scripts/canonicalize-node-modules.ts}
+        bun --bun ${./scripts/normalize-bun-binaries.ts}
 
         runHook postBuild
       '';