Group the panel by what operations say they are about

A strip of groups over the adjust panel — Light, Colour, Detail — derived
from the attributes the operations declare. `adjust.slint` names none of
them: the strings arrive resolved and the panel only draws them, so a new
operation joins the right group by saying what it is and this file does not
change (FR-DEV-3a).

A group nothing carries is not offered, so a tab never opens onto nothing.
Geometry is left out because its one operation prefers an on-canvas widget
and is skipped by the row builder — a Geometry tab would be empty while
`GeometryPanel` holds the real controls. The strip appears only when there
is more than one group to choose between; a single tab is a control with one
option.

The selected group is underlined rather than filled. The accent means
*modified* everywhere else in this interface, and spending it on "which tab"
would blunt the one signal the panel has.

**The trap, and it nearly bit again.** `op_index` on a row counts over every
capability, not over the ones a filter kept — it is how a row routes back to
the core. Renumbering it while filtering would make a slider drive a
different operation, which looks like a rendering fault rather than a
routing one. `rows_filtered` keeps `enumerate` over the full list and only
`group_head` is a position within the emitted rows; a test moves a value
through a filtered row and checks it lands where it was asked to.

Six tests, including that a nonsense index falls back to showing everything
rather than to showing nothing.

ui/dr-ui/ui/adjust.slint

@@ -630,6 +630,14 @@ export component TransferPanel inherits VerticalLayout {
 
 export component AdjustPanel inherits Rectangle {
     in property <[ParamRow]> rows;
+    /// The groups worth offering, derived from what the operations say they
+    /// are about. **This file names none of them** — the strings arrive
+    /// already resolved and the panel only has to draw them, which is what
+    /// keeps a new operation a zero-edit change here (FR-DEV-3a).
+    in property <[string]> tabs;
+    /// Index into `tabs`, or -1 for "everything".
+    in property <int> active-tab: -1;
+    callback tab-picked(int);
     in property <bool> enabled: true;
     /// The tone curve's sampled shape, evaluated in Rust by the same spline
     /// the shader runs so the drawn line cannot disagree with the applied one.
@@ -677,6 +685,50 @@ export component AdjustPanel inherits Rectangle {
 
         if !root.enabled: Caption { text: "No image"; }
 
+        // The group strip. Only when there is more than one group to choose
+        // between — a single tab is a control with one option, which is
+        // decoration.
+        if root.enabled && root.tabs.length > 1: HorizontalLayout {
+            spacing: Theme.gap-sm;
+            alignment: start;
+
+            all := TouchArea {
+                width: 34px;
+                height: Theme.touch-target;
+                mouse-cursor: pointer;
+                clicked => { root.tab-picked(-1); }
+                Label {
+                    text: "All";
+                    emphasised: root.active-tab == -1 || all.has-hover;
+                    vertical-alignment: center;
+                }
+            }
+
+            for tab[i] in root.tabs: tab-area := TouchArea {
+                width: label.preferred-width + 8px;
+                height: Theme.touch-target;
+                mouse-cursor: pointer;
+                clicked => { root.tab-picked(i); }
+
+                label := Label {
+                    text: tab;
+                    emphasised: root.active-tab == i || tab-area.has-hover;
+                    vertical-alignment: center;
+                }
+
+                // The selected group is underlined rather than filled: the
+                // accent means *modified* everywhere else in this interface,
+                // and spending it on "which tab" would blunt the one signal
+                // the panel has (ui-refinement.md, principle 2).
+                Rectangle {
+                    y: parent.height - 2px;
+                    height: 2px;
+                    width: parent.width;
+                    background: root.active-tab == i ? Theme.ink : transparent;
+                }
+            }
+        }
+
         // No Flickable here any more. The histogram, the capture metadata and
         // the geometry controls sat *above* this one and could not be scrolled
         // away, so on a 280px column in portrait they ate the height the