feat: make keepass the default backend with master.kdbx default path

Change default backend from "geheim" to "keepass" and default KDBXPath
from ~/Documents/Keepass/master to ~/Documents/Keepass/master.kdbx.
Existing geheim users must set backend="geheim" in ~/.config/foostore.json.
Update resolveBackend fallback, struct comments, and test assertions to match.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/internal/cli/cli.go b/internal/cli/cli.go
index 75ab078..1f5a736 100644
--- a/internal/cli/cli.go
+++ b/internal/cli/cli.go
@@ -187,7 +187,9 @@ func newCLI(ctx context.Context, backendName, kdbxPath string) (*CLI, error) {
 }
 
 // resolveBackend returns the effective backend name given the flag override and
-// the config value.  flag takes precedence; empty strings fall back to "geheim".
+// the config value.  flag takes precedence; config value is used next; the
+// last-resort default is "keepass" (matching the config.defaultConfigWithHome
+// default so that the two sources of truth stay in sync).
 func resolveBackend(flagValue, cfgValue string) string {
 	if flagValue != "" {
 		return flagValue
@@ -195,7 +197,7 @@ func resolveBackend(flagValue, cfgValue string) string {
 	if cfgValue != "" {
 		return cfgValue
 	}
-	return "geheim"
+	return "keepass"
 }
 
 // buildBackend constructs the Backend and its associated Gitter based on