fix(store): expand a leading ~ in EMCLI_DB

A literal "~/..." in EMCLI_DB has no shell to expand it, so SQLite opened
it relative to the cwd and silently created a stray "~" directory tree.
Expand a leading "~" or "~/" to the user's home dir; "~user", mid-path
tildes, and absolute/relative paths are left untouched.

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

internal/store/store.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strconv"
+	"strings"
 
 	_ "modernc.org/sqlite"
 )
@@ -77,10 +78,24 @@ func (s *Store) migrate() error {
 
 func (s *Store) Close() error { return s.db.Close() }
 
+// expandUserHome replaces a leading "~" or "~/" in p with the user's home
+// directory. Only a leading tilde is expanded (the usual shell convention) —
+// "~user" and a tilde elsewhere in the path are left untouched. This guards
+// against an EMCLI_DB set to a literal "~/..." (no shell to expand it), which
+// would otherwise be opened relative to the cwd and create a stray "~" dir.
+func expandUserHome(p string) string {
+	if p == "~" || strings.HasPrefix(p, "~/") {
+		if home, err := os.UserHomeDir(); err == nil {
+			return filepath.Join(home, strings.TrimPrefix(p[1:], "/"))
+		}
+	}
+	return p
+}
+
 // DefaultDBPath resolves EMCLI_DB or the per-OS default location.
 func DefaultDBPath() (string, error) {
 	if p := os.Getenv("EMCLI_DB"); p != "" {
-		return p, nil
+		return expandUserHome(p), nil
 	}
 	if runtime.GOOS == "windows" {
 		if dir := os.Getenv("AppData"); dir != "" {