feat(apps): add isAppTool helper in core (#1260) (#1272)

* feat(apps): add isAppTool helper in core (#1260)

Adds @modelcontextprotocol/ext-apps as a dependency (root + clients/web)
and a thin core/mcp/apps.ts wrapper exposing:

- getAppResourceUri(tool): re-export of getToolUiResourceUri so all
  Inspector clients consume the same nested/flat _meta resolution.
- isAppTool(tool): boolean predicate built on top of getAppResourceUri.

Both surface the underlying ext-apps throw on a malformed _meta.ui.resourceUri
(string that does not start with "ui://") rather than swallowing it — server
bugs should be visible.

Tests cover nested format, deprecated flat format, nested-wins precedence,
missing _meta, and the invalid-URI throw.

Refs #1260

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* test(apps): address PR #1272 review feedback

- core/mcp/apps.ts: convert getAppResourceUri from a typed const re-export to
  a function declaration so its export style matches isAppTool. Behavior is
  unchanged.
- core/mcp/apps.ts: document the filter-iteration implication on isAppTool —
  callers using tools.filter(isAppTool) will halt on a server-malformed URI.
- apps.test.ts: add the symmetric isAppTool false-case for `_meta.ui` present
  without `resourceUri`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

package.json

@@ -24,6 +24,7 @@
     "test:coverage": "cd ./clients/web/ && npm run test:coverage"
   },
   "dependencies": {
+    "@modelcontextprotocol/ext-apps": "^1.7.1",
     "@modelcontextprotocol/sdk": "^1.29.0",
     "zod": "^4.3.6"
   }