feat(ui): clarification des contrôles d'en-tête DockControls (#42)

Refinement UX suite #26 : clarifie les contrôles DockControls dans
l'en-tête des panneaux. Frontend-pur.

QA vert : tsc --noEmit exit 0, vitest 62 fichiers / 616 tests passés.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/features/projects/ProjectsView.docking.test.tsx

@@ -68,7 +68,7 @@ describe("ProjectsView view docking (#22)", () => {
     expect(dialog).toBeTruthy();
 
     // Dock it to the left via the header control.
-    fireEvent.click(within(dialog).getByRole("button", { name: "dock Git left" }));
+    fireEvent.click(within(dialog).getByRole("button", { name: "Ancré à gauche — Git" }));
 
     // The modal window is gone; the Git view now lives in the left dock column.
     await waitFor(() =>
@@ -85,13 +85,13 @@ describe("ProjectsView view docking (#22)", () => {
 
     openPanelFloating("Git");
     const dialog = await screen.findByRole("dialog", { name: "Git" });
-    fireEvent.click(within(dialog).getByRole("button", { name: "dock Git left" }));
+    fireEvent.click(within(dialog).getByRole("button", { name: "Ancré à gauche — Git" }));
 
     const leftDock = await screen.findByRole("complementary", { name: "left dock" });
     const leftHeader = within(leftDock).getByLabelText("Git panel");
     // Move it to the right dock from the docked header control.
     fireEvent.click(
-      within(leftHeader).getByRole("button", { name: "dock Git right" }),
+      within(leftHeader).getByRole("button", { name: "Ancré à droite — Git" }),
     );
 
     await waitFor(() =>
@@ -109,7 +109,7 @@ describe("ProjectsView view docking (#22)", () => {
     fireEvent.click(
       within(await screen.findByRole("dialog", { name: "Git" })).getByRole(
         "button",
-        { name: "dock Git left" },
+        { name: "Ancré à gauche — Git" },
       ),
     );
     // Dock Agents right.
@@ -117,7 +117,7 @@ describe("ProjectsView view docking (#22)", () => {
     fireEvent.click(
       within(await screen.findByRole("dialog", { name: "Agents" })).getByRole(
         "button",
-        { name: "dock Agents right" },
+        { name: "Ancré à droite — Agents" },
       ),
     );
 

frontend/src/features/projects/ProjectsView.tsx

@@ -40,9 +40,11 @@ import {
   Button,
   DockRegion,
   FloatingWindow,
+  IconButton,
   Input,
   MenuBar,
   Panel,
+  cn,
   zIndex,
   type FloatingWindowSize,
   type MenuBarItem,
@@ -469,58 +471,72 @@ export function ProjectsView() {
   const rightPanels = panelsDockedTo(placements, "right");
   const floatingList = floatingPanels(placements);
 
-  // Placement toggle buttons for a view's header — the "flottant ↔ ancré
+  // Placement controls for a view's header — labelled icon-buttons aligned 1:1
-  // (gauche/droite)" control from the contract. The button for the current slot
+  // with the « Panneaux » menu wording (#42). Order: ⇤ gauche · ⇥ droite · □
-  // is disabled so the active placement reads at a glance.
+  // flottant · ↗ fenêtre détachée · × fermé. The *current* placement reads as
+  // ACTIVE (aria-pressed + ring), never disabled — a disabled control loses its
+  // tooltip/keyboard focus and conflates "impossible" with "already selected".
+  // Only genuinely-impossible actions are disabled (detach with no active
+  // project). All labelling flows through `title` + `aria-label`; no visible
+  // text. The detach control is hidden for the main-window-only `projects` view.
   function DockControls({ panel }: { panel: PanelId }) {
     const placement = placementOf(placements, panel);
     const title = PANEL_TITLE[panel];
+    // Active (current-placement) styling — visually distinct, still clickable.
+    const activeClass = "bg-raised text-content ring-1 ring-border-strong";
     return (
       <div className="flex shrink-0 items-center gap-1">
-        <Button
+        <IconButton
           size="sm"
-          variant="ghost"
+          title="Ancré à gauche"
-          aria-label={`dock ${title} left`}
+          aria-label={`Ancré à gauche — ${title}`}
-          disabled={isDockedTo(placement, "left")}
+          aria-pressed={isDockedTo(placement, "left")}
+          className={cn(isDockedTo(placement, "left") && activeClass)}
           onClick={() => setPlacement(panel, { dock: "left" })}
         >
-          ◧
+          ⇤
-        </Button>
+        </IconButton>
-        <Button
+        <IconButton
           size="sm"
-          variant="ghost"
+          title="Ancré à droite"
-          aria-label={`dock ${title} right`}
+          aria-label={`Ancré à droite — ${title}`}
-          disabled={isDockedTo(placement, "right")}
+          aria-pressed={isDockedTo(placement, "right")}
+          className={cn(isDockedTo(placement, "right") && activeClass)}
           onClick={() => setPlacement(panel, { dock: "right" })}
         >
-          ◨
+          ⇥
-        </Button>
+        </IconButton>
-        <Button
+        <IconButton
           size="sm"
-          variant="ghost"
+          title="Flottant"
-          aria-label={`float ${title}`}
+          aria-label={`Flottant — ${title}`}
-          disabled={placement === "floating"}
+          aria-pressed={placement === "floating"}
+          className={cn(placement === "floating" && activeClass)}
           onClick={() => setPlacement(panel, "floating")}
         >
-          ⧉
+          □
-        </Button>
+        </IconButton>
-        <Button
+        {panel !== "projects" && (
+          <IconButton
             size="sm"
-          variant="ghost"
+            title="Fenêtre détachée"
-          aria-label={`open ${title} in new window`}
+            aria-label={`Fenêtre détachée — ${title}`}
-          disabled={!active || isDetached(placement)}
+            aria-pressed={isDetached(placement)}
+            disabled={!active}
+            className={cn(isDetached(placement) && activeClass)}
             onClick={() => detachPanel(panel)}
           >
-          ⤢
+            ↗
-        </Button>
+          </IconButton>
-        <Button
+        )}
+        <IconButton
           size="sm"
-          variant="ghost"
+          title="Fermé"
-          aria-label={`close ${title}`}
+          aria-label={`Fermé — ${title}`}
           onClick={() => closePanel(panel)}
         >
-          ✕
+          ×
-        </Button>
+        </IconButton>
       </div>
     );
   }