[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/tools/get-roots-list.ts

@@ -0,0 +1,76 @@
+import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
+
+// Tool configuration
+const name = "get-roots-list";
+const config = {
+  title: "Get Roots List Tool",
+  description:
+    "Lists the current MCP roots provided by the client. Demonstrates the roots protocol capability even though this server doesn't access files.",
+  inputSchema: {},
+};
+
+/**
+ * Registers the 'get-roots-list' tool with the given MCP server.
+ *
+ * If the client does not support the roots protocol, the tool is not registered.
+ *
+ * The registered tool interacts with the MCP roots protocol, which enables the server to access information about
+ * the client's workspace directories or file system roots. When supported by the client, the server retrieves
+ * and formats the current list of roots for display.
+ *
+ * Key behaviors:
+ * - Determines whether the connected MCP client supports the roots protocol by checking client capabilities.
+ * - Fetches and formats the list of roots, including their names and URIs, if supported by the client.
+ * - Handles cases where roots are not supported, or no roots are currently provided, with explanatory messages.
+ *
+ * @param {McpServer} server - The server instance interacting with the MCP client and managing the roots protocol.
+ */
+export const registerGetRootsListTool = (server: McpServer) => {
+  const clientSupportsRoots =
+    server.server.getClientCapabilities()?.roots?.listChanged;
+  if (!clientSupportsRoots) {
+    server.registerTool(
+      name,
+      config,
+      async (args, extra): Promise<CallToolResult> => {
+        const currentRoots = (await server.server.listRoots()).roots;
+        if (currentRoots.length === 0) {
+          return {
+            content: [
+              {
+                type: "text",
+                text:
+                  "The client supports roots but no roots are currently configured.\n\n" +
+                  "This could mean:\n" +
+                  "1. The client hasn't provided any roots yet\n" +
+                  "2. The client provided an empty roots list\n" +
+                  "3. The roots configuration is still being loaded",
+              },
+            ],
+          };
+        }
+
+        const rootsList = currentRoots
+          .map((root, index) => {
+            return `${index + 1}. ${root.name || "Unnamed Root"}\n   URI: ${
+              root.uri
+            }`;
+          })
+          .join("\n\n");
+
+        return {
+          content: [
+            {
+              type: "text",
+              text:
+                `Current MCP Roots (${currentRoots.length} total):\n\n${rootsList}\n\n` +
+                "Note: This server demonstrates the roots protocol capability but doesn't actually access files. " +
+                "The roots are provided by the MCP client and can be used by servers that need file system access.",
+            },
+          ],
+        };
+      }
+    );
+  }
+};