feat(web): expandable resource_link with read-on-demand (#1449) (#1456)

* feat(web): expandable resource_link with read-on-demand (#1449)

Replace the placeholder `resource_link` rendering in ContentViewer with a
dedicated, Mantine-native `ResourceLink` element that mirrors V1's behavior:

- Shows uri (monospace, link-styled), optional name/description, and a
  mimeType badge.
- Expand/collapse affordance (chevron + loading spinner) that is keyboard
  accessible (native button: role, aria-expanded, aria-label, Enter/Space).
- On first expand, reads the linked resource on demand via an injected
  callback and renders the full read result inline as formatted JSON under a
  green "Resource:" label, capped to a max height with scroll for large
  results. The fetched result is cached across collapse/expand.

The read handler is threaded as a "dumb component + callback as prop" through
ToolResultPanel → ToolsScreen → InspectorView, with App supplying a handler
that returns the `ReadResourceResult` from `inspectorClient.readResource`.

Also extract the shared `resourceContentsToBlock` helper into
`utils/resourceContents.ts` (previously private to ResourcePreviewPanel).

Tests: unit coverage for ResourceLink (collapsed/expanded/error/cache) and
the ContentViewer wiring, plus Storybook stories with play functions.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(web): scroll large resource_link read results within the card

A plain ScrollArea with only `mah` does not scroll when its parent (the
content-sized card) has no definite height, so a large read result overflowed
the card instead of scrolling. Switch to ScrollArea.Autosize, which grows with
content up to the max height and then scrolls. Adds a LargeResult story
covering the bounded-scroll behavior.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* refactor(web): make ResourceLink a group; extract ResourceLinkInfo element

ResourceLink is stateful (expand/loading/cached result) and fetches data via
a callback — group-like behavior, and the only `elements/` component using
useState. Move it to `groups/` and split out the pure-display metadata as a
new `elements/ResourceLinkInfo` element (uri/name/description/mime + an
optional action slot).

This keeps the layer dependencies clean (no element→group import, which
moving ResourceLink alone would have introduced):
- ContentViewer (element) renders ResourceLinkInfo (element) statically for
  `resource_link` blocks and no longer takes an onReadResource prop.
- ToolResultPanel (group) renders the interactive ResourceLink (group) for
  `resource_link` blocks, ContentViewer for the rest.
- ResourceLink (group) composes ResourceLinkInfo + ContentViewer.

Also reverts the now-single-consumer resourceContents.ts extraction, restoring
ResourcePreviewPanel's local toContentBlock.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(web): make ResourceLink read retryable and guard double-fetch

Address PR review: a failed read is no longer cached as terminal — only
a successful result is cached, so collapsing and re-expanding retries the
read after a transient failure. Add a loading guard so toggling while a
read is in flight does not fire a redundant second read.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* style(web): prettier formatting for ResourceLink test

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore: remove accidentally-committed build artifacts; gitignore clients/*/build

A stray 'git add -A' swept 8 compiled build files into d25c9382. Remove
them from tracking and add clients/*/build to .gitignore so client build
output is never committed again.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/web/src/components/groups/ToolResultPanel/ToolResultPanel.test.tsx

@@ -1,7 +1,11 @@
 import { describe, it, expect, vi } from "vitest";
 import userEvent from "@testing-library/user-event";
 import type { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
-import { renderWithMantine, screen } from "../../../test/renderWithMantine";
+import {
+  renderWithMantine,
+  screen,
+  waitFor,
+} from "../../../test/renderWithMantine";
 import { ToolResultPanel } from "./ToolResultPanel";
 
 const okResult: CallToolResult = {
@@ -37,6 +41,34 @@ describe("ToolResultPanel", () => {
     expect(screen.getByText("No results yet")).toBeInTheDocument();
   });
 
+  it("renders a resource_link block as an expandable ResourceLink", async () => {
+    const user = userEvent.setup();
+    const onReadResource = vi.fn().mockResolvedValue({
+      contents: [{ uri: "demo://r/1", text: "linked body" }],
+    });
+    const result: CallToolResult = {
+      content: [
+        { type: "text", text: "ok" },
+        { type: "resource_link", uri: "demo://r/1", name: "Linked" },
+      ],
+    };
+    renderWithMantine(
+      <ToolResultPanel
+        result={result}
+        onClear={() => {}}
+        onReadResource={onReadResource}
+      />,
+    );
+    expect(screen.getByText("ok")).toBeInTheDocument();
+    await user.click(
+      screen.getByRole("button", { name: "Expand resource demo://r/1" }),
+    );
+    expect(onReadResource).toHaveBeenCalledWith("demo://r/1");
+    await waitFor(() =>
+      expect(screen.getByText(/"linked body"/)).toBeInTheDocument(),
+    );
+  });
+
   it("invokes onClear when Clear is clicked", async () => {
     const user = userEvent.setup();
     const onClear = vi.fn();