Fix snapshot-test CRLF mismatch on Windows runners

The control-query snapshot tests panicked on the Windows GitHub runner
because git's default core.autocrlf=true converted fixture files
(src/control/snapshots/*.json) to CRLF on checkout, while the
in-memory JSON output is LF. trim_end() only strips trailing newlines,
not interior \r, so every snapshot comparison mismatched.

Two defenses:

1. .gitattributes: pin src/control/snapshots/*.json to text eol=lf so
   future Windows checkouts keep the fixtures LF-only regardless of
   local git config.

2. src/control/queries.rs (assert_snapshot): replace \r\n with \n in
   the expected text before comparison, so any future
   re-introduction of CRLF (a contributor with non-LF editor settings,
   a different runner, etc.) doesn't surface as a snapshot mismatch.

.gitattributes

@@ -0,0 +1,5 @@
+# Keep snapshot test fixtures LF-only across all platforms so that
+# Windows checkouts with core.autocrlf=true don't convert them to CRLF
+# (which would mismatch the actual JSON serialization output during
+# snapshot comparison).
+src/control/snapshots/*.json text eol=lf

src/control/queries.rs

@@ -1272,6 +1272,9 @@ mod tests {
         }
         let expected = std::fs::read_to_string(&path)
             .unwrap_or_else(|e| panic!("failed to read snapshot {}: {e}", path.display()));
+        // Normalize line endings: Windows checkouts with core.autocrlf=true
+        // convert fixture files to CRLF; the in-memory JSON output is LF.
+        let expected = expected.replace("\r\n", "\n");
         // Tolerate trailing newline differences from editors.
         if expected.trim_end() != actual.trim_end() {
             panic!(