feat(ui): content-measured History columns, shared caption widths, settings_view split

Stage 5: generalize logColumnWidth into textColumnWidth so History's
Trigger/Job/State/Detail/Log columns size from measured text instead of
pixel constants that clipped at larger text sizes (F6, F14).

Stage 6: captionColumnWidth replaces detailCaptionWidth and
settingsLabelWidth with one theme-derived helper; jobs_view_details.go
now builds its metadata rows and their width from a single
metadataRows() list instead of two hand-kept ones (F10); the Settings
button row drops its transparent-rectangle spacers for a
CustomPaddedLayout (F8); the remaining eight fyne.TextTruncate call
sites move to the non-deprecated Truncation field (N1).

Stage 7: settings_view.go split into settings_view.go (field
construction/save/load/validate), settings_view_layout.go (the
two-column layout and settingsSection/settingsRow), and
settings_view_helpers.go (fyneVersion, dialogs, path helpers),
mirroring the jobs_view.go split. Along the way, Queue/Storage's inline
VBox and Application/About's settingsSection collapse into one
settingsSection(title, spacing, rows...) constructor, and
chooseFile/chooseJSONFile merge into one function with a filter
argument.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/ui/jobs_view_test.go

@@ -35,8 +35,8 @@ func TestFolderOptionsAlwaysIncludesSentinels(t *testing.T) {
 func TestFolderOptionsAppendsUniqueFolders(t *testing.T) {
 	jobs := []domain.Job{
 		{Folder: "Maintenance"},
-		{Folder: ""},           // no folder → not a named folder
-		{Folder: "  Backups "}, // trimmed to "Backups"
+		{Folder: ""},            // no folder → not a named folder
+		{Folder: "  Backups "},  // trimmed to "Backups"
 		{Folder: "Maintenance"}, // duplicate → not added again
 	}
 	opts := folderOptions(jobs)
@@ -412,6 +412,29 @@ func TestToolbarButtonRedrawsRowAndDetails(t *testing.T) {
 	}
 }
 
+// TestDetailCaptionWidthCoversEveryCaption is the guard that makes the single
+// metadataRows list self-enforcing (F10): every caption it returns must
+// measure no wider than captionColumnWidth's result for that same list, or a
+// row added to metadataRows without updating the width measurement would
+// silently truncate.
+func TestDetailCaptionWidthCoversEveryCaption(t *testing.T) {
+	testApp := test.NewApp()
+	defer testApp.Quit()
+
+	d := newDetailsPanel(job{}, &domain.JobRuntime{}, domain.OverlapPolicySkip, 0)
+	specs := d.metadataRows()
+	captions := make([]string, len(specs))
+	for i, spec := range specs {
+		captions[i] = spec.caption
+	}
+	capW := captionColumnWidth(captions...)
+	for _, c := range captions {
+		if w := widget.NewLabelWithStyle(c, fyne.TextAlignLeading, fyne.TextStyle{Bold: true}).MinSize().Width; w > capW {
+			t.Errorf("caption %q measures %v, wider than captionColumnWidth's %v", c, w, capW)
+		}
+	}
+}
+
 func TestViewToggleTextNamesTheAction(t *testing.T) {
 	cases := []struct {
 		current domain.JobListView