[WIP] Refactor everything server to be more modular and use recommended APIs.

Adding Trigger Elicitation Request and Get Roots List tools

* Updated architecture.md

* Added roots.ts
  - tracks roots by sessionId
  - setRootsListChangedHandler
    - listens for roots changed notification from the client
      - updates the roots map by sessionId
      - sends log notification or error to the client

* In server/index.ts
  - import setRootsListChangedHandler
  - in clientConnected callback
    - call setRootsListChangedHandler passing server and sessionId

* In sse.ts, stdio.ts, and streamableHttp.ts
  - receive clientConnected from server factory
  - call clientConnected when server is connected to transport
* Added get-roots-list.ts
  - registerGetRootsListTool
    - Registers the 'get-roots-list' tool with the given MCP server.

* Added trigger-elicitation-request.ts
  - registerTriggerElicitationRequestTool
    - registered tool sends an elicitation request that exercises all supported field types

* In tools/index.ts
  - imports registerTriggerElicitationRequestTool and registerGetRootsListTool
  - in registerTools
    - call registerTriggerElicitationRequestTool and registerGetRootsListTool, passing server

src/everything/server/roots.ts

@@ -0,0 +1,63 @@
+import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import {
+  Root,
+  RootsListChangedNotificationSchema,
+} from "@modelcontextprotocol/sdk/types.js";
+
+// Track roots by session id
+const roots: Map<string | undefined, Root[]> = new Map<
+  string | undefined,
+  Root[]
+>();
+
+/**
+ * Sets a handler for the "RootsListChanged" notification from the client.
+ *
+ * This handler updates the local roots list when notified and logs relevant
+ * acknowledgement or error.
+ *
+ * @param {McpServer} mcpServer - The instance of the McpServer managing server communication.
+ * @param {string | undefined} sessionId - An optional session ID used for logging purposes.
+ */
+export const setRootsListChangedHandler = (
+  mcpServer: McpServer,
+  sessionId?: string
+) => {
+  const server = mcpServer.server;
+
+  // Set the notification handler
+  server.setNotificationHandler(
+    RootsListChangedNotificationSchema,
+    async () => {
+      try {
+        // Request the updated roots list from the client
+        const response = await server.listRoots();
+        if (response && "roots" in response) {
+          // Store the roots list for this client
+          roots.set(sessionId, response.roots);
+
+          // Notify the client of roots received
+          await server.sendLoggingMessage(
+            {
+              level: "info",
+              logger: "everything-server",
+              data: `Roots updated: ${response.roots.length} root(s) received from client`,
+            },
+            sessionId
+          );
+        }
+      } catch (error) {
+        await server.sendLoggingMessage(
+          {
+            level: "error",
+            logger: "everything-server",
+            data: `Failed to request roots from client: ${
+              error instanceof Error ? error.message : String(error)
+            }`,
+          },
+          sessionId
+        );
+      }
+    }
+  );
+};