fix(wallet): let a switch restart an adopted (external) daemon

Switching to a named wallet failed every time when the app had connected to a
pre-existing dragonxd at startup: the daemon is flagged externalDaemonDetected,
so stopEmbeddedDaemon()'s policy is DisconnectOnly ("not ours to stop") and the
switch skips the stop entirely. The old daemon keeps the RPC port, and the
relaunch fast-fails on EmbeddedDaemon::start()'s isPortInUse check — misread as a
bad wallet, reverting after a ~40s hang on the process-handle-only run-wait
(which reads false immediately for an adopted daemon).

A switch legitimately needs to restart the node, so:
- App::stopDaemonForWalletSwitch(): for an adopted daemon, send a graceful RPC
  "stop" using the creds we actually connected with (saved_config_) — only our
  own daemon obeys it, so a foreign dragonxd is a safe no-op — then wait (bounded
  ~40s) for the RPC port to actually free (isRpcPortInUse, the same gate start()
  uses). Owned daemons take the normal stopEmbeddedDaemon() path. No PID/name kill
  is ever issued at an adopted daemon.
- switchToWallet: gate start() on the port actually freeing; if it doesn't,
  abort with a distinct switch_stop_failed_ reason instead of starting into a busy
  port. Clear the external latch before relaunch so the fresh process is owned.
- EmbeddedDaemon::clearExternalDaemonDetected() (+ controller forwarder).
- Accurate revert message: "the running node didn't release its connection in
  time" vs. the bad-wallet message.

Root-caused from live Windows logs; design + implementation adversarially
verified. Note: beginAdoptSeedWallet has the identical pattern and is left for a
separate fund-critical review.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/daemon/embedded_daemon.h

@@ -142,6 +142,10 @@ public:
      * When true the wallet should connect to it instead of showing an error.
      */
     bool externalDaemonDetected() const { return external_daemon_detected_; }
+    // Clear the adopted-external latch before relaunching our OWN process (e.g. a wallet switch that
+    // stopped the adopted daemon), so the freshly spawned daemon is treated as owned. start() also
+    // clears it on the port-free fall-through, but only if not short-circuited by an early guard.
+    void clearExternalDaemonDetected() { external_daemon_detected_ = false; }
 
     /**
      * @brief Set callback for state changes