fix(node): detect a wallet salvage at startup, not only on connect

Reported: loading a BDB-inconsistent wallet silently renamed it and created a new
one — no recovery dialog. Two causes, both fixed:

1) Detection ran only in onConnected(). The salvage happens at STARTUP, and the
   node may never connect (block-index abort, long sync, crash) — or a long sync
   trims the salvage line out of the rolling output buffer before connect. Extract
   detectWalletAutoRecovery() and run it every tryConnect() tick (every ~5s during
   startup), so the salvage is caught the instant it appears, regardless of whether
   the node connects. Also hold the crash-restart loop while a salvage is pending,
   so the wallet can't be re-salvaged/shrunk while the Rebuild/Restore dialog is up.

2) walletAutoRecovered() only matched the SUCCESSFUL-salvage strings. A
   BDB-inconsistent file makes aggressive salvage FAIL ("found no records"), which
   prints different lines. Broaden the detector to the signals that fire in every
   case: "CDBEnv::Salvage", the "Renamed <wallet> to wallet.<ts>.bak" rename, and
   "found no records in wallet" — while still not matching normal startup or a
   block-DB abort.

Adds the exact failed-salvage sequence to the detector test. Build clean, suite
green (1/1).

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

src/app.h

@@ -1344,6 +1344,7 @@ private:
     void renderBlockDbReindexDialog();    // offer to rebuild an unreadable block database (-reindex)
     void reindexBlockDatabase();          // restart the daemon with -reindex to rebuild the block DB
     void renderWalletRecoveredDialog();   // warn that the node auto-recovered/salvaged wallet.dat
+    void detectWalletAutoRecovery();      // scan daemon output for a salvage; fire the warning once/session
     void restoreOriginalWallet();         // swap the wallet.<ts>.bak back over the salvaged copy + restart
     void pumpWalletRestore();             // main-thread: surface the restore/rebuild op's result
     void rebuildWalletDatabase();         // rebuild a BDB-inconsistent wallet into a loadable one (helper)