feat(FN-687): relocate ProjectSelector to header-left group

- Move ProjectSelector from standalone header section into header-left div next to logo/title
- Change dropdown positioning from right-aligned to left-aligned with higher z-index
- Update CSS to use inline-flex and relative positioning for proper containment
- Adjust mobile styles for narrower max-width within header-left
- Add test verifying ProjectSelector renders inside header-left container

packages/dashboard/app/components/Header.tsx

@@ -170,6 +170,20 @@ export function Header({
         <h1 className="logo">Fusion</h1>
         <span className="logo-sub">tasks</span>
 
+        {/* Project Selector - shown when 2+ projects, placed next to logo/title */}
+        {projects.length > 1 && (
+          <div className="header-project-selector">
+            <ProjectSelector
+              projects={projects}
+              currentProject={currentProject || null}
+              onSelect={(project) => {
+                onSelectProject?.(project);
+              }}
+              onViewAll={onViewAllProjects || (() => {})}
+            />
+          </div>
+        )}
+        
         {/* Back to All Projects button when viewing a specific project */}
         {currentProject && onViewAllProjects && (
           <button
@@ -184,20 +198,6 @@ export function Header({
         )}
       </div>
 
-      {/* Project Selector - shown when 2+ projects */}
-      {projects.length > 1 && (
-        <div className="header-project-selector">
-          <ProjectSelector
-            projects={projects}
-            currentProject={currentProject || null}
-            onSelect={(project) => {
-              onSelectProject?.(project);
-            }}
-            onViewAll={onViewAllProjects || (() => {})}
-          />
-        </div>
-      )}
-
       <div className="header-actions">
         {/* Desktop Search - only show in board view */}
         {onSearchChange && view === "board" && !isMobile && (

packages/dashboard/app/components/__tests__/Header.test.tsx

@@ -559,6 +559,27 @@ describe("Header", () => {
     expect(screen.getByTestId("project-selector-trigger")).toBeDefined();
   });
 
+  it("renders ProjectSelector within header-left when multiple projects exist", () => {
+    const projects = [
+      { id: "proj_1", name: "Project One", path: "/path/1", status: "active" as const, isolationMode: "in-process" as const, createdAt: "", updatedAt: "" },
+      { id: "proj_2", name: "Project Two", path: "/path/2", status: "active" as const, isolationMode: "in-process" as const, createdAt: "", updatedAt: "" },
+    ];
+    const { container } = render(
+      <Header
+        projects={projects}
+        currentProject={projects[0]}
+        onSelectProject={vi.fn()}
+        onViewAllProjects={vi.fn()}
+      />
+    );
+    // ProjectSelector should be inside header-left, not a sibling
+    const headerLeft = container.querySelector(".header-left");
+    expect(headerLeft).not.toBeNull();
+    const selectorInLeft = headerLeft!.querySelector(".header-project-selector");
+    expect(selectorInLeft).not.toBeNull();
+    expect(selectorInLeft!.querySelector("[data-testid='project-selector-trigger']")).not.toBeNull();
+  });
+
   it("does not show ProjectSelector with single project", () => {
     const projects = [
       { id: "proj_1", name: "Project One", path: "/path/1", status: "active" as const, isolationMode: "in-process" as const, createdAt: "", updatedAt: "" },

packages/dashboard/app/styles.css

@@ -131,11 +131,11 @@ body {
   position: relative;
 }
 
-/* Project selector in header */
+/* Project selector in header (inside header-left) */
 .header-project-selector {
-  display: flex;
+  display: inline-flex;
   align-items: center;
-  margin: 0 var(--space-md);
+  position: relative;
   flex-shrink: 1;
   min-width: 0;
 }
@@ -1522,8 +1522,8 @@ body {
 .project-selector__dropdown {
   position: absolute;
   top: calc(100% + 8px);
-  right: 0;
-  z-index: 50;
+  left: 0;
+  z-index: 100;
   min-width: 320px;
   max-width: min(420px, 90vw);
   max-height: min(70vh, 520px);
@@ -4175,8 +4175,7 @@ body {
 
   /* Project selector mobile adjustments */
   .header-project-selector {
-    margin: 0 8px;
-    max-width: 140px;
+    max-width: 120px;
     flex-shrink: 1;
   }