fix tmux-monitor tailscale issue (#1076)

* Initial plan

* fix(tmux-monitor): explicitly handle tailscale auth in PanePreview hostConfig

For Tailscale-auth hosts the pane-preview attach path was building the
Terminal hostConfig with only the generic spread of host fields.  This
could omit or mismap auth-critical details and trigger a plain TCP/SSH
reachability path that doesn't work with Tailscale-only SSH endpoints.

The fix branches on `host.authType === "tailscale"` and:
- Carries `authType: "tailscale"` explicitly so the backend always selects
  the Tailscale-aware PTY path regardless of how the host object evolves.
- Derives `port` from `host.sshPort ?? host.port` so Tailscale SSH
  endpoints on a non-default SSH port are reached correctly.
- Leaves all non-tailscale auth types on the unchanged code path.

Reattach (bumping instanceId + attachNonce) continues to work because
terminalHostConfig is recomputed on every render with the latest
instanceIdRef.current value.

* refactor(tmux-monitor): simplify tailscale port logic with extracted variable

Address code review feedback: extract resolvedPort into a local variable
to avoid the duplicated `host.sshPort ?? host.port` expression that was
assigned to both `port` and `sshPort`.  Restructure as an if/else block
instead of an IIFE for readability.

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

src/ui/features/tmux-monitor/PanePreview.tsx

@@ -70,6 +70,36 @@ export function PanePreview({
     setAttachNonce((n) => n + 1);
   }
 
+  // For Tailscale-auth hosts the generic pane-preview attach path can fail
+  // host-reachability checks because the connection is initiated as a plain
+  // TCP/SSH dial rather than through the Tailscale transport that was used for
+  // the interactive terminal.  Building the hostConfig with an explicit
+  // authType and a defensively derived SSH port ensures the backend selects
+  // the correct Tailscale-aware PTY path for both initial attach and reattach.
+  let terminalHostConfig: TerminalHostConfig;
+  if (host.authType === "tailscale") {
+    // Prefer host.sshPort when set (Tailscale SSH can be on a non-standard
+    // port); fall back to the general host.port.
+    const resolvedPort = host.sshPort ?? host.port;
+    terminalHostConfig = {
+      ...host,
+      port: resolvedPort,
+      sshPort: resolvedPort,
+      // Carry authType explicitly to guard against accidental omission
+      // in the spread (e.g. if host object shape changes upstream).
+      authType: "tailscale",
+      instanceId: instanceIdRef.current,
+    } as TerminalHostConfig;
+  } else {
+    const resolvedPort = host.sshPort ?? host.port;
+    terminalHostConfig = {
+      ...host,
+      port: resolvedPort,
+      sshPort: resolvedPort,
+      instanceId: instanceIdRef.current,
+    } as TerminalHostConfig;
+  }
+
   return (
     <>
       <div className="flex items-center gap-3 border-b border-border px-3 py-1.5 text-xs text-muted-foreground">
@@ -147,13 +177,7 @@ export function PanePreview({
         <CommandHistoryProvider key={attachNonce}>
           <Terminal
             ref={terminalRef}
-            hostConfig={
-              {
-                ...host,
-                sshPort: host.port,
-                instanceId: instanceIdRef.current,
-              } as TerminalHostConfig
-            }
+            hostConfig={terminalHostConfig}
             isVisible={true}
             title={pane.sessionName}
             showTitle={false}