fix(nix): use jq -j to preserve exact file content in hook generation

jq -r appends a trailing newline to output, making the hook file 1 byte
larger than what rtk verify expects. This causes the integrity check to
fail with a hash mismatch. jq -j outputs raw strings without adding a
trailing newline, preserving the exact content.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Author: helgeu

nix/homeManagerModule.nix

@@ -29,7 +29,7 @@ rtkPackages: {
       relpath=$(jq -r ".files[$i].path" manifest.json)
       mode=$(jq -r ".files[$i].mode" manifest.json)
       mkdir -p "$out/$(dirname "$relpath")"
-      jq -r ".files[$i].content" manifest.json > "$out/$relpath"
+      jq -j ".files[$i].content" manifest.json > "$out/$relpath"
       chmod "$mode" "$out/$relpath"
     done
   '';