feat(tabs): cross-device tab sync via conversation lifecycle

Consume the conversation lifecycle handoff ([email protected], [email protected]).
Re-pinned file: deps + re-mirrored .dispatch/*.reference.md.

- fetchOpenConversations() on connect: GET /conversations?status=active,idle
  restores the tab bar across devices (merges with localStorage — opens new
  tabs, removes closed ones, updates titles from backend)
- conversation.statusChanged WS handler: closed → removeTabLocally (no
  re-POST); active → open tab + spinner; idle → update status map
- conversation.compacted WS handler: dispose stale store + cache, reload
  history from server
- TabBar shows a spinner on active conversations (statusFor prop)
- closeTab refactored to use removeTabLocally (extracted cleanup)
- conformance guards + WS adapter tests cover all 3 new WsServerMessage types

686 tests green.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/app/App.svelte b/src/app/App.svelte
index 2b3b250..e065759 100644
--- a/src/app/App.svelte
+++ b/src/app/App.svelte
@@ -257,6 +257,7 @@
 			<TabBar
 				tabs={store.tabs}
 				activeConversationId={store.activeConversationId}
+				statusFor={(id) => store.conversationStatus(id)}
 				onSelect={(id) => store.selectTab(id)}
 				onClose={(id) => store.closeTab(id)}
 				onNewDraft={() => store.newDraft()}