sbbuilder: list the default manifests, and keep them on the first edit

The helper replaces its default [manifests] table with the file's, so
adding one manifest to a file without the table dropped neovim's, and
the page showed no rows for the default that was in effect. With no
table in the file the page now lists the helper's defaults, and the
first add, remove or URL edit writes them all before its own change.
Toml.js gains sections(), to tell a missing table from an empty one.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/desktop/modules/sbbuilder/SbbVmModule.qml b/desktop/modules/sbbuilder/SbbVmModule.qml
index 45c7216..97e7983 100644
--- a/desktop/modules/sbbuilder/SbbVmModule.qml
+++ b/desktop/modules/sbbuilder/SbbVmModule.qml
@@ -114,6 +114,7 @@ Module {
                         width: col.width
                         wrapMode: Text.Wrap
                         text: "A package's upstream deps list; {VERSION} is the new version. A hint update moves the package's extra downloads to the versions listed there."
+                              + (col.st.manifestsDefault ? " These are the helper's defaults, not in the file: the first change writes them all, then adds or removes its own." : "")
                         color: Theme.subtext
                         font { family: Theme.fontFamily; pixelSize: Theme.fontSize - 4 }
                     }