feat(store): add account from_address field + v2 migration

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

internal/store/store.go

@@ -42,15 +42,35 @@ func Open(path string) (*Store, error) {
 		return nil, fmt.Errorf("apply schema: %w", err)
 	}
 	s := &Store{db: db}
-	if _, err := s.GetSetting("schema_version"); err != nil {
-		if err := s.SetSetting("schema_version", strconv.Itoa(schemaVersion)); err != nil {
-			db.Close()
-			return nil, err
-		}
+	if err := s.migrate(); err != nil {
+		db.Close()
+		return nil, err
 	}
 	return s, nil
 }
 
+// migrate brings an existing database up to the current schemaVersion. A brand-
+// new database (no schema_version yet) already has every column from schemaSQL,
+// so it is simply stamped at the current version. Each older version runs its
+// forward step. The version gate makes every step idempotent across reopens.
+func (s *Store) migrate() error {
+	v, err := s.GetSetting("schema_version")
+	if err != nil {
+		// Fresh database: schemaSQL created all columns already.
+		return s.SetSetting("schema_version", strconv.Itoa(schemaVersion))
+	}
+	ver, _ := strconv.Atoi(v)
+	if ver < 2 {
+		if _, err := s.db.Exec(`ALTER TABLE accounts ADD COLUMN from_address TEXT`); err != nil {
+			return fmt.Errorf("migrate to v2: %w", err)
+		}
+		if err := s.SetSetting("schema_version", "2"); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (s *Store) Close() error { return s.db.Close() }
 
 // DefaultDBPath resolves EMCLI_DB or the per-OS default location.