Avoid the indented-string warning in the Radar swap layout

[TyceHerrman]

Nova emits a
broken-string-indentation warning at
flake.nix:740

The Radar replacement string starts with sidebar = ''{. Because the opening
brace is on the first line, it participates in indentation calculation and
prevents the intended stripping of indentation. This is nonfatal, but it adds
warnings to downstream package and Home Manager evaluations.

Reproduction

run:

nix-instantiate --parse flake.nix > /dev/null

Lix reports that text on the first line of the multiline string disables
indentation stripping and points to the opening brace.

Proposed fix

Start the content on the next line and indent the block consistently:

sidebar = ''
  {
    plugin location="radar"
  }
'';

Keep the existing pkgs.replaceVars call and Radar layout structure. Update
the repository's LOC scorecard for the two additional source lines.

Validation and acceptance

A local patch against 352f1f77d97a82cd4e0769b90a02d0b26a571fc5 passed Nix
parsing. Evaluating the corrected string produced no warning, and substituting
it into layout.swap.kdl preserved the existing non-whitespace token sequence.
This verifies parsing and the intended whitespace-only change; it is not a
full package build or interactive layout test.

Acceptance: package evaluation no longer emits this indentation warning, and
the existing layout check still accepts both open and collapsed Radar layouts.

The previously merged #624 addressed
a different indented string in the old Home Manager module.

[TyceHerrman]

Downstream tracking update: I have now wired this indentation fix into my Nix configuration, applied automatically to official Nova main revision e1610fb026542e829bda61e84b078739a94a6899 before its flake is evaluated.

The full aarch64-darwin package manifest for yazelix-no-rio-no-helix-no-yazi, including the manifest phase of my update-pins run, now evaluates without this indentation warning. I also apply the shared Crane pname fix from marktoda/zj-radar#42 to Nova's locked Yazelix/zj-radar@1be7d73417fc15d5403734e2e2312296573a111e; the same evaluation emits no Crane placeholder-name warnings.

This uses source patches, with no upstream revision changes. Only Radar's locked source is replaced by the patched path and NAR hash; its original input specification, dependency graph, and nixpkgs follows relationship remain intact. Regression checks cover both patched sources being evaluated and incompatible upstream changes failing visibly.

This verifies actual package evaluation, not a Rust build or interactive layout test.