fix(web): read modern tasks support from the extension map

SEP-2663 moved task support from `capabilities.tasks` to the negotiated
`capabilities.extensions["io.modelcontextprotocol/tasks"]`, but the
Connection Info modal's capability grid tested only for the top-level
key. A modern server that advertised the extension in `server/discover`
therefore showed "Tasks ✗" while the very same extension id was listed
under "Server Extensions" two sections below.

Server capability rows now fall back to an extension id for the
capabilities the modern era expresses that way (tasks is the only one
today), gated on the negotiated era so a legacy connection is still
judged purely on its `initialize` capabilities. Keyed the same way
`InspectorClient.isTasksExtensionNegotiated()` gates the Tasks tab, so
the checkmark and the tab can't disagree.

Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/components/groups/ConnectionInfoContent/ConnectionInfoContent.stories.tsx

@@ -77,6 +77,14 @@ export const ModernEra: Story = {
       },
     },
   },
+  // SEP-2663 moved task support to the extension map, so the Tasks capability
+  // row must read it there on a modern connection — otherwise a tasks-capable
+  // server shows ✗ while listing the extension below (#1887).
+  play: async ({ canvasElement }) => {
+    const canvas = within(canvasElement);
+    const tasksRow = canvas.getByText("Tasks");
+    await expect(tasksRow.previousElementSibling).toHaveTextContent("✓");
+  },
 };
 
 // A modern server that omitted the optional `_meta` serverInfo stamp (#1772).