Integrate Context-Engine RAG service for enhanced LLM responses

Backend:
- Created context-engine/client.ts - HTTP client for Context-Engine API
- Created context-engine/service.ts - Lifecycle management of Context-Engine sidecar
- Created context-engine/index.ts - Module exports
- Created server/routes/context-engine.ts - API endpoints for status/health/query

Integration:
- workspaces/manager.ts: Trigger indexing when workspace becomes ready (non-blocking)
- index.ts: Initialize ContextEngineService on server start (lazy mode)
- ollama-cloud.ts: Inject RAG context into chat requests when available

Frontend:
- model-selector.tsx: Added Context-Engine status indicator
  - Green dot = Ready (RAG enabled)
  - Blue pulsing dot = Indexing
  - Red dot = Error
  - Hidden when Context-Engine not running

All operations are non-blocking with graceful fallback when Context-Engine is unavailable.

packages/ui/src/components/model-selector.tsx

@@ -1,7 +1,7 @@
 import { Combobox } from "@kobalte/core/combobox"
-import { createEffect, createMemo, createSignal, onCleanup, onMount } from "solid-js"
+import { createEffect, createMemo, createSignal, onCleanup, onMount, Show } from "solid-js"
 import { providers, fetchProviders } from "../stores/sessions"
-import { ChevronDown } from "lucide-solid"
+import { ChevronDown, Database } from "lucide-solid"
 import type { Model } from "../types/session"
 import { getLogger } from "../lib/logger"
 import { getUserScopedKey } from "../lib/user-storage"
@@ -29,6 +29,11 @@ export default function ModelSelector(props: ModelSelectorProps) {
   const [isOpen, setIsOpen] = createSignal(false)
   const qwenAuth = useQwenOAuth()
   const [offlineModels, setOfflineModels] = createSignal<Set<string>>(new Set())
+
+  // Context-Engine status: "stopped" | "ready" | "indexing" | "error"
+  type ContextEngineStatus = "stopped" | "ready" | "indexing" | "error"
+  const [contextEngineStatus, setContextEngineStatus] = createSignal<ContextEngineStatus>("stopped")
+
   let triggerRef!: HTMLButtonElement
   let searchInputRef!: HTMLInputElement
 
@@ -64,9 +69,28 @@ export default function ModelSelector(props: ModelSelectorProps) {
     }
     window.addEventListener("opencode-zen-offline-models", handleCustom as EventListener)
     window.addEventListener("storage", handleStorage)
+
+    // Poll Context-Engine status
+    const pollContextEngine = async () => {
+      try {
+        const response = await fetch("/api/context-engine/status")
+        if (response.ok) {
+          const data = await response.json() as { status: ContextEngineStatus }
+          setContextEngineStatus(data.status ?? "stopped")
+        } else {
+          setContextEngineStatus("stopped")
+        }
+      } catch {
+        setContextEngineStatus("stopped")
+      }
+    }
+    pollContextEngine()
+    const pollInterval = setInterval(pollContextEngine, 5000)
+
     onCleanup(() => {
       window.removeEventListener("opencode-zen-offline-models", handleCustom as EventListener)
       window.removeEventListener("storage", handleStorage)
+      clearInterval(pollInterval)
     })
   })
 
@@ -170,6 +194,29 @@ export default function ModelSelector(props: ModelSelectorProps) {
                 {currentModelValue() && isOfflineModel(currentModelValue() as FlatModel) && (
                   <span class="selector-badge selector-badge-warning">Offline</span>
                 )}
+                {/* Context-Engine RAG Status Indicator */}
+                <Show when={contextEngineStatus() !== "stopped"}>
+                  <span
+                    class="inline-flex items-center gap-1 text-[10px]"
+                    title={
+                      contextEngineStatus() === "ready"
+                        ? "Context Engine is active - RAG enabled"
+                        : contextEngineStatus() === "indexing"
+                          ? "Context Engine is indexing files..."
+                          : "Context Engine error"
+                    }
+                  >
+                    <span
+                      class={`w-2 h-2 rounded-full ${contextEngineStatus() === "ready"
+                          ? "bg-emerald-500"
+                          : contextEngineStatus() === "indexing"
+                            ? "bg-blue-500 animate-pulse"
+                            : "bg-red-500"
+                        }`}
+                    />
+                    <Database class="w-3 h-3 text-zinc-400" />
+                  </span>
+                </Show>
               </span>
               {currentModelValue() && (
                 <span class="selector-trigger-secondary">