feat(web/ui): unify session opening and add repo card in project list

- Add openSession utility with tab deduplication/focus
- Use openSession in navbar live sessions, use-instance-actions, and project tool links
- Pass onAddRepository to ProjectListItem and add dashed 'Add Repository' card
- Style add-repo card in projects.css

apps/web/src/hooks/use-instance-actions.ts

@@ -1,4 +1,4 @@
-import { useState, useCallback, useRef } from "react";
+import { useState, useCallback } from "react";
 import {
 	stopInstance,
 	deleteInstance,
@@ -8,6 +8,7 @@ import {
 } from "../api/sessions";
 import type { Session } from "../api/sessions";
 import { useSessions } from "../state/sessions";
+import { openSession } from "../utils/open-session";
 
 interface UseInstanceActionsOptions {
 	onRefresh: () => Promise<void>;
@@ -37,27 +38,9 @@ export function useInstanceActions(
 		null,
 	);
 	const [dirtyDeleteFiles, setDirtyDeleteFiles] = useState<string[]>([]);
-	const tabRefs = useRef<Map<string, Window | null>>(new Map());
 
 	const handleOpen = useCallback((session: Session) => {
-		const key = session.id;
-		const existing = tabRefs.current.get(key);
-		if (existing && !existing.closed) {
-			existing.focus();
-			return;
-		}
-
-		let url: string;
-		if (session.url) {
-			url = session.url;
-		} else if (session.tool_type_interfaces?.includes("terminal")) {
-			url = `/instances/${session.id}/terminal`;
-		} else {
-			url = `/projects/${session.project_id}`;
-		}
-
-		const w = window.open(url, `session-${session.id}`);
-		tabRefs.current.set(key, w);
+		openSession(session);
 	}, []);
 
 	const handleStart = useCallback(