Slice 3 wave A: tabs model, model selector, cache delete, localStorage

- features/tabs: pure tab-workspace reducer (create/select/close/setModel/
  setTitle/deriveTitle, draft=null active) + injected-persistence runes store
- features/chat: mutable per-tab model (setModel) + delta routing guard
  (ignore foreign conversationId) + ModelSelector.svelte + DaisyUI chat bubbles
  / composer (keeps streaming <details> keying fix)
- features/conversation-cache: surface delete(conversationId) on the wrapper
  for tab-close local-forget
- adapters/local-storage: generic injected JSON localStore<T> (quota/corrupt-safe)

Verified: svelte-check 0/0, vitest 273, biome clean, build ok.

1 files changed, 24 insertions, 0 deletions

diff --git a/src/features/conversation-cache/cache.test.ts b/src/features/conversation-cache/cache.test.ts
index c68ed0d..89e81b8 100644
--- a/src/features/conversation-cache/cache.test.ts
+++ b/src/features/conversation-cache/cache.test.ts
@@ -171,3 +171,27 @@ describe("cache.evictIfOverBudget", () => {
 		expect(evicted).toEqual([]);
 	});
 });
+
+describe("cache.delete", () => {
+	it("removes the conversation from the store", async () => {
+		const store = createFakeStore();
+		const cache = createConversationCache(store);
+
+		await store.append("conv-1", [chunk(1), chunk(2)]);
+		await cache.delete("conv-1");
+
+		const stored = await store.load("conv-1");
+		expect(stored).toEqual([]);
+	});
+
+	it("then load returns []", async () => {
+		const store = createFakeStore();
+		const cache = createConversationCache(store);
+
+		await cache.commit("conv-1", [chunk(1), chunk(2), chunk(3)]);
+		await cache.delete("conv-1");
+
+		const result = await cache.load("conv-1");
+		expect(result).toEqual([]);
+	});
+});