feat(transport): CLI endpoints + conversation.open broadcast (Wave 2)

transport-http: GET /conversations (list with ?q= prefix filter),
GET /conversations/:id/last (blocks until turn settles, returns last AI
text), POST /conversations/:id/open (emits conversationOpened hook),
PUT /conversations/:id/title (set title). emit threaded from host.emit.
extractLastAssistantText pure helper. 21 new tests (166 total).

transport-ws: subscribes to conversationOpened hook, broadcasts
ConversationOpenMessage to all connected WS clients. 2 new tests.

session-orchestrator: conversationOpened hook descriptor (exported).

1 files changed, 5 insertions, 1 deletions

diff --git a/packages/transport-http/src/seam.ts b/packages/transport-http/src/seam.ts
index 43c9d4d..1c89a34 100644
--- a/packages/transport-http/src/seam.ts
+++ b/packages/transport-http/src/seam.ts
@@ -5,6 +5,10 @@ export { credentialStoreHandle } from "@dispatch/credential-store";
 export type { LspServerStatus, LspService } from "@dispatch/lsp";
 export { lspServiceHandle } from "@dispatch/lsp";
 export type { SessionOrchestrator, WarmService } from "@dispatch/session-orchestrator";
-export { cacheWarmHandle, sessionOrchestratorHandle } from "@dispatch/session-orchestrator";
+export {
+	cacheWarmHandle,
+	conversationOpened,
+	sessionOrchestratorHandle,
+} from "@dispatch/session-orchestrator";
 export type { ThroughputStore } from "@dispatch/throughput-store";
 export { ThroughputQueryError, throughputStoreHandle } from "@dispatch/throughput-store";