fix: close three stale-completion holes from the round-16 suppressed block (#2144)

Copilot's round 16 reported "no new comments", but its suppressed block carried
three real findings.

- `AuthTab` released `clearInFlightRef` before checking whether the completion
  was still current, so server A settling after the user moved to B and started
  a clear there dropped B's lock and let a second B clear run concurrently
  against the same store entry. `current()` is now checked before either shared
  ref is touched: a stale clear owns nothing.
- Switching servers retired the clear but left `ownClearRef` set. The retired
  clear returns before its `oauthRevision` bump, so the marker had no bump to
  skip and would swallow the first unrelated revision on the newly selected
  server, stranding that server's banner.
- The web session check compared only the server id, which a
  disconnect/reconnect to the SAME server passes — that flow builds a
  replacement `InspectorClient`, so the old clear would have run its
  session-wide cleanup against the new session. The client identity is part of
  the check now.

Both new tests were verified to fail with their fix reverted.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0177mPHAdECD18nLLCTwR5rh
Signed-off-by: cliffhall <cliff@futurescale.com>

clients/tui/__tests__/AuthTab.test.tsx

@@ -187,6 +187,46 @@ describe("AuthTab", () => {
     expect(onClearOAuth).toHaveBeenCalledTimes(2);
   });
 
+  // A stale completion owns nothing: server A settling after the user moved to
+  // B and started a clear there must not drop B's lock, or a second B clear
+  // could run concurrently against the same store entry.
+  it("a stale completion does not release the current server's lock", async () => {
+    const settlers: Array<() => void> = [];
+    const onClearOAuth = vi.fn(
+      () =>
+        new Promise<void>((resolve) => {
+          settlers.push(resolve);
+        }),
+    );
+    const props = (serverName: string) => ({
+      ...baseProps,
+      serverName,
+      onClearOAuth,
+      inspectorClient: null,
+      oauthStatus: "idle" as const,
+      oauthMessage: null,
+      focused: true,
+    });
+    const { stdin, rerender } = render(<AuthTab {...props("a")} />);
+    await tick();
+
+    stdin.write("s"); // A's clear starts
+    await tick();
+    rerender(<AuthTab {...props("b")} />);
+    await tick();
+    stdin.write("s"); // B's clear starts
+    await tick();
+    expect(onClearOAuth).toHaveBeenCalledTimes(2);
+
+    // A settles late. B's clear is still running, so its lock must hold.
+    settlers[0]!();
+    await tick();
+    stdin.write("s");
+    await tick();
+
+    expect(onClearOAuth).toHaveBeenCalledTimes(2);
+  });
+
   // A rejection is NOT a revocation failure — those come back as outcomes and
   // are reported through the message line. This is the local clear or the
   // disconnect itself failing, so reporting success would be a plain lie.