refactor: reorganize CSS and Tool Workshop page

- Extract styles.css into styles/ directory (tokens, global, utilities, syntax-highlight, pages)
- Extract ToolWorkshopPage into components:
  - ToolTypeListSidebar, ToolTypeEditorPanel, ToolWorkshopMobileView
  - use-tool-workshop hook for state management
- Slim ToolWorkshopPage from 1,269 to 110 lines

Quality gates: tsc --noEmit passes, npm run build passes

apps/web/src/styles/pages/sessions.css

@@ -0,0 +1,69 @@
+/* Mobile Sessions Page */
+@media (max-width: 767px) {
+	.sessions-page {
+		padding: var(--space-2);
+	}
+
+	.sessions-page .page-header {
+		margin-bottom: var(--space-3);
+	}
+
+	.sessions-page .page-header h1 {
+		font-size: 1.25rem;
+	}
+
+	.last-session-section {
+		margin-bottom: var(--space-4);
+	}
+
+	.last-session-section h2 {
+		font-size: 1rem;
+		margin-bottom: var(--space-2);
+	}
+
+	.create-session-section {
+		padding: var(--space-3);
+	}
+
+	.create-session-section h2 {
+		font-size: 1rem;
+		margin-bottom: var(--space-2);
+	}
+}
+
+.session-card-actions.mobile {
+	display: flex;
+	gap: var(--space-2);
+	padding-top: var(--space-3);
+	border-top: 1px solid var(--color-border);
+}
+
+.session-card-actions.mobile .mobile-primary {
+	flex: 1;
+	justify-content: center;
+	min-height: 44px;
+	padding: var(--space-2) var(--space-3);
+}
+
+.session-card-actions.mobile .mobile-more {
+	min-width: 44px;
+	min-height: 44px;
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	padding: var(--space-2);
+}
+@media (max-width: 767px) {
+	.create-session-form .form-row {
+		grid-template-columns: 1fr;
+		gap: var(--space-3);
+	}
+
+	.create-session-form input,
+	.create-session-form select,
+	.create-session-form textarea,
+	.create-session-form button {
+		min-height: 44px;
+	}
+}
+