slosh: layout files are *.layout, not *.layout.kdl

The old name argued that the extension should say how to read the
file. The argument lost to a collision: zellij speaks the same KDL
syntax under that same extension with a different schema, and to
anyone arriving from there .kdl said *whose* file it is -- naming the
wrong owner is worse than not naming the parser. So a layout is
x.layout, a project's is slosh.layout, the name says what the file is
and --check says how it was read. (It is still KDL underneath; point
your editor's highlighting at *.layout.)

Nobody's checked-in workspace vanishes on upgrade: the project scan
still finds slosh.layout.kdl, never writes it, and where both
spellings exist the new one wins, because two files disagreeing needs
one answer. The unparseable-file heuristic in --check learned the new
suffix -- it matched '.layout.' with a trailing dot, which the new
name no longer has.

The webdemo overlay moves with it (demo.layout), rebuilt and
boot-checked.

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/test_config.py b/tests/test_config.py
index cb80829..84d73c7 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -713,8 +713,8 @@ def test_the_shipped_files_are_what_they_claim():
     check(
         "config/config.kdl lints clean", conf.returncode == 0, repr(conf.stderr[:160])
     )
-    lay = root / "config" / "example.layout.kdl"
-    check("the example layout is named `*.layout.kdl`", lay.exists(), str(lay))
+    lay = root / "config" / "example.layout"
+    check("the example layout is named `*.layout`", lay.exists(), str(lay))
     exl = subprocess.run([BIN, "--check", str(lay)], capture_output=True, text=True)
     check("and it lints clean as a layout", exl.returncode == 0, repr(exl.stderr[:200]))
     out = subprocess.run(