review: harden version read + fix MonitoringScreen docstring

Address PR #1641 review feedback:

- Add readInspectorVersionSafe() (non-throwing) in core/node/version.ts and use
  it in the web backend, so a failure to resolve the root manifest hides the
  (cosmetic) version badge instead of crashing the backend at startup. Covered
  by tests for both the resolved and unresolvable paths.
- Update MonitoringScreen's docstrings: it now wraps every supplied screen in a
  ScreenStage (only the active tab mounts, cross-fading) rather than rendering
  just the active tab's node.

The third fetch-consolidation suggestion (one useInitialConfig instead of three
GET /api/config hooks) is tracked as a follow-up in #1643.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BrihGWcrM9JGRyu41nzZYw

clients/web/src/test/integration/node/version.test.ts

@@ -11,6 +11,7 @@ import { join, dirname } from "path";
 import { pathToFileURL, fileURLToPath } from "url";
 import {
   readInspectorVersion,
+  readInspectorVersionSafe,
   ROOT_PACKAGE_NAME,
 } from "@inspector/core/node/version.js";
 
@@ -67,3 +68,19 @@ describe("readInspectorVersion", () => {
     }
   });
 });
+
+describe("readInspectorVersionSafe", () => {
+  it("returns the version when the root manifest resolves", () => {
+    expect(readInspectorVersionSafe(import.meta.url)).toBe(readRootVersion());
+  });
+
+  it("returns undefined instead of throwing when the root can't be resolved", () => {
+    // A caller rooted in the OS temp dir (outside the repo) has no inspector
+    // root manifest above it — readInspectorVersion would throw, but the safe
+    // variant swallows it so a cosmetic version read never crashes the caller.
+    const callerUrl = pathToFileURL(
+      join(tmpdir(), "nowhere", "caller.js"),
+    ).href;
+    expect(readInspectorVersionSafe(callerUrl)).toBeUndefined();
+  });
+});