feat: bound connect attempts with a 30 s default connectionTimeout (#2320)

connectionTimeout defaulted to 0, which InspectorClient.connect() read as
"no bound at all" — so out of the box nothing the Inspector owns bounded a
connect attempt, and the only thing ending a hung handshake was the SDK's
60 s per-request timeout on initialize, reporting "Request timed out".

- Add DEFAULT_CONNECTION_TIMEOUT_MS (30000) to core/mcp/types.ts. An absent
  value resolves to it on the client, on disk read, in the web form draft,
  and in the CLI's header-only settings shell. An explicit 0 keeps its
  documented meaning (no timeout; --connect-timeout 0) and is now persisted
  so the opt-out round-trips; the default is the omit-sentinel, as for
  taskTtl.
- Key the post-timeout transport teardown to the timer actually firing, not
  to connectionTimeout > 0 — otherwise a non-zero default would tear down
  every failed connect, including a recoverable 401 whose transport the
  auth recovery holds open.
- The timeout message names the bound and where to raise it: "Connection
  timed out after N ms. To accommodate a slower server, you may increase
  the timeout value in Server Settings."
- The CLI's UNREACHABLE classifier now matches that message.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01M4h8Xa6Ed9zwtv5ojX35MT
Signed-off-by: cliffhall <cliff@futurescale.com>

clients/cli/__tests__/error-handler.test.ts

@@ -133,6 +133,21 @@ describe("classifyError", () => {
     expect(classifyError(err).exitCode).toBe(EXIT_CODES.UNREACHABLE);
   });
 
+  it("classifies InspectorClient's connect-time timeout as UNREACHABLE (#2320)", () => {
+    // The core's Promise.race rejection reads "Connection timed out after …",
+    // which the older `connect timed out` alternation never matched — so the
+    // one timeout the Inspector itself owns fell through to the generic exit
+    // code. Now that it fires by default (30 s), it has to classify with the
+    // rest of the network-layer failures.
+    const err = new Error(
+      "Connection timed out after 30000 ms. To accommodate a slower server, " +
+        "you may increase the timeout value in Server Settings.",
+    );
+    const { exitCode, envelope } = classifyError(err);
+    expect(exitCode).toBe(EXIT_CODES.UNREACHABLE);
+    expect(envelope.code).toBe("unreachable");
+  });
+
   it("falls back to USAGE for an unrecognized Error", () => {
     expect(classifyError(new Error("something else")).exitCode).toBe(
       EXIT_CODES.USAGE,