feat(web,hub): export session conversation (#808)

* test: reproduce issue #793

* fix: add session conversation export (closes #793)

* fix(hub): sort session export by display time for invoked scheduled messages

Export now uses COALESCE(invoked_at, created_at) ordering so JSON/Markdown
exports match the visible chat chronology after scheduled messages are invoked.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(web): escape newlines in session export YAML front matter

Prevent session metadata containing newlines or quotes from breaking
Markdown export front matter.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

web/src/api/client.ts

@@ -19,6 +19,7 @@ import type {
     SkillsResponse,
     SpawnResponse,
     VisibilityPayload,
+    HapiSessionExport,
     SessionResponse,
     SessionsResponse
 } from '@/types/api'
@@ -241,6 +242,13 @@ export class ApiClient {
         return await this.request<SessionResponse>(`/api/sessions/${encodeURIComponent(sessionId)}`)
     }
 
+    async getSessionExport(sessionId: string, options?: { signal?: AbortSignal }): Promise<HapiSessionExport> {
+        return await this.request<HapiSessionExport>(
+            `/api/sessions/${encodeURIComponent(sessionId)}/export`,
+            { signal: options?.signal }
+        )
+    }
+
     async getMessages(
         sessionId: string,
         options: {