feat: implement full breadcrumb path navigation in Files tab

- Add breadcrumbPath array to app state for tracking folder hierarchy
- Rewrite updateBreadcrumb() to render full path: Home > folder > subfolder
- Each breadcrumb segment is clickable to navigate back to that level
- Current folder shown in bold (non-clickable), parent folders as links
- Reset breadcrumb path on tab switch, home navigation, and initial load
- Update navigateFolder/selectFolder to push to breadcrumb path
- Enhanced breadcrumb CSS with hover effects and dark mode support

static/css/layout/content.css

@@ -0,0 +1,38 @@
+/* Content area */
+.content-area {
+	flex-grow: 1;
+	padding: 20px;
+	overflow-y: scroll;
+	scrollbar-gutter: stable;
+}
+
+.page-title {
+	font-size: 24px;
+	font-weight: bold;
+	margin-bottom: 20px;
+	color: #2d3748;
+}
+
+.actions-bar {
+	display: flex;
+	justify-content: space-between;
+	margin-bottom: 20px;
+}
+
+.action-buttons {
+	display: flex;
+	gap: 12px;
+}
+
+.empty-state {
+	display: flex;
+	flex-direction: column;
+	align-items: center;
+	justify-content: center;
+	padding: 40px;
+	text-align: center;
+	color: #888;
+	width: 100%;
+	height: 300px;
+	grid-column: 1 / -1;
+}