Fix shared workspace close semantics

Allow shared execution workspace sessions to be archived with warnings instead of hard-blocking on open linked issues, clear issue workspace links when those shared sessions are archived, and update the close dialog copy and coverage.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/routes/execution-workspaces.ts

@@ -1,7 +1,7 @@
 import { and, eq } from "drizzle-orm";
 import { Router } from "express";
 import type { Db } from "@paperclipai/db";
-import { projects, projectWorkspaces } from "@paperclipai/db";
+import { issues, projects, projectWorkspaces } from "@paperclipai/db";
 import { updateExecutionWorkspaceSchema } from "@paperclipai/shared";
 import { validate } from "../middleware/validate.js";
 import { executionWorkspaceService, logActivity, workspaceOperationService } from "../services/index.js";
@@ -303,6 +303,21 @@ export function executionWorkspaceRoutes(db: Db) {
       }
       workspace = archivedWorkspace;
 
+      if (existing.mode === "shared_workspace") {
+        await db
+          .update(issues)
+          .set({
+            executionWorkspaceId: null,
+            updatedAt: new Date(),
+          })
+          .where(
+            and(
+              eq(issues.companyId, existing.companyId),
+              eq(issues.executionWorkspaceId, existing.id),
+            ),
+          );
+      }
+
       try {
         await stopRuntimeServicesForExecutionWorkspace({
           db,