Card: lead with CoreAIKit ChatSession (kit-enrolled)

README.md

@@ -43,11 +43,22 @@ iPhone 17 Pro** — the [zoo](https://github.com/john-rocky/coreai-model-zoo) sh
 
 ## Use it
 
-This bundle runs in **[CoreAIChat](https://github.com/john-rocky/coreai-model-zoo/tree/main/apps/CoreAIChat)**
-(the zoo's on-device chat app): pick **Youtu-LLM 2B** in the model picker; the app downloads
-`gpu-pipelined/youtu_llm_2b_decode_absorbed_msdpa/` from this repo into `Documents/models/` on
-first run, then loads from the local cache. 2B (≥2 GB) bundles need the app's
-`com.apple.developer.kernel.increased-memory-limit` entitlement (CoreAIChat ships it).
+**[CoreAIKit](https://github.com/john-rocky/coreai-kit)** (SPM) — one line, on-device:
+
+```swift
+import CoreAIKit
+
+let chat = try await ChatSession(catalog: "youtu-llm-2b")
+let reply = try await chat.respond(to: "What can you do, offline?")
+// downloads this repo once, then runs fully on-device; the <think> reasoning
+// arrives as .thinking events, reply.content is the final answer
+```
+
+Or the [ChatDemo runner](https://github.com/john-rocky/coreai-kit/tree/main/Examples/ChatDemo)
+(GUI + `swift run chat-cli --model youtu-llm-2b`), or the zoo's
+[CoreAIChat](https://github.com/john-rocky/coreai-model-zoo/tree/main/apps/CoreAIChat) app
+(pick **Youtu-LLM 2B**). 2B (≥2 GB) bundles need the host app's
+`com.apple.developer.kernel.increased-memory-limit` entitlement.
 
 Engine contract (decode-only static-`[1,1]` graph): set `COREAI_CHUNK_THRESHOLD=1` before engine
 creation (prefill runs as pipelined S=1 steps); don't call `engine.warmup()` (it warms query