gui: offer to convert a Berkeley DB wallet to SQLite on first run

A first-run dialog for an existing wallet.dat with no backend choice yet:
"Convert to SQLite" exports the wallet and records the sqlite marker so
the next start opens it; "Keep Berkeley DB" records that choice so the
offer does not return; "Decide later" leaves no marker and asks again.
wallet.dat is never touched, and the change takes effect on restart --
matching the restart-to-apply model.

The conversion itself is DoConvertWalletToSQLite(), a headless-testable
function the button calls: it reuses the export path (extracted as
ExportActiveWalletToSQLite, shared with -walletsqliteexport, which keeps
its own specific messages), refuses if already on SQLite or if a
wallet.sqlite exists, and writes the marker only after a verified export.

New wallet-convert self-test proves the action end to end: build a
Berkeley DB wallet, convert, and confirm wallet.sqlite + the marker are
written, wallet.dat is left untouched, a second convert refuses, and a
flagless restart opens the converted SQLite wallet with its phrase intact.
All wallet suites pass. The modal itself is thin UI over this tested
action.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/walletcmd.h b/src/walletcmd.h
index d993856..38cbfdb 100644
--- a/src/walletcmd.h
+++ b/src/walletcmd.h
@@ -75,6 +75,15 @@ int CmdWalletStorageCheck();
 // not change which backend the runtime wallet opens.
 int CmdWalletSQLiteExport(const std::string& strDest);
 
+// Export the currently-loaded wallet to a SQLite file (shared by the command
+// above and the GUI wizard). Returns false with an error on any failure.
+bool ExportActiveWalletToSQLite(const std::string& strDest, int& nCopiedRet,
+                                std::string& strErrorRet);
+
+// Convert the running Berkeley DB wallet to SQLite and record the backend
+// marker so the next start opens it. wallet.dat is left untouched as fallback.
+bool DoConvertWalletToSQLite(int& nCopiedRet, std::string& strErrorRet);
+
 // Diagnostic/migration staging: compare a SQLite wallet export with the current
 // wallet.dat raw records. Prints counts only, never record keys or values.
 int CmdWalletSQLiteVerify(const std::string& strPath);