Add OpenRouter chat provider; fix Windows load errors (0.17.0).

- OpenRouter as an alternative chat provider: server-side API key
  (settings.json or OPENROUTER_API_KEY), model list with vision marks and
  filter, SSE streaming, images as data URLs. Memory embeddings stay on Ollama;
  park/warm LLM are no-ops for the remote provider.
- AssistentSaveKnowledgeAttach: JArray param is not supported by SwarmUI API
  reflection and aborted registration of every later API call; use string[].
- SQLite bootstrap: preload native e_sqlite3 for the current OS/arch
  (win/osx/linux) and resolve DllImport to it.
- settings.json: shared-read + atomic write with retry to avoid Windows
  sharing violations.
- csproj: fix MSB4012 in the native SQLite copy target.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

AssistentKnowledgeApi.cs

@@ -83,7 +83,8 @@ public partial class SwarmAssistentExtension
         };
     }
 
-    public async Task<JObject> AssistentSaveKnowledgeAttach(Session session, string persona, JArray attach)
+    /// <remarks>SwarmUI's API reflection has no JArray coercer — <c>string[]</c> is the supported list type.</remarks>
+    public async Task<JObject> AssistentSaveKnowledgeAttach(Session session, string persona, string[] attach = null)
     {
         await Task.CompletedTask;
         string pid = AssistentConfig.SafeId(persona);
@@ -104,9 +105,9 @@ public partial class SwarmAssistentExtension
             JArray cleaned = [];
             if (attach is not null)
             {
-                foreach (JToken t in attach)
+                foreach (string t in attach)
                 {
-                    string id = AssistentConfig.SafeId(t?.ToString());
+                    string id = AssistentConfig.SafeId(t);
                     if (id is not null)
                     {
                         cleaned.Add(id);