feat: add SQLite support, setup wizard enhancements, and live dashboard

Add zero-dependency SQLite mode so users can run Erupe without
PostgreSQL. A transparent db.DB wrapper auto-translates PostgreSQL
SQL ($N placeholders, now(), ::casts, ILIKE, public. prefix,
TRUNCATE) for SQLite at runtime — all 28 repo files use the wrapper
with no per-query changes needed.

Setup wizard gains two new steps: quest file detection with download
link, and gameplay presets (solo/small/community/rebalanced). The API
server gets a /dashboard endpoint with auto-refreshing stats.

CI release workflow now builds and pushes Docker images to GHCR
alongside binary artifacts on tag push.

Key changes:
- common/db: DB/Tx wrapper with 6 SQL translation rules
- server/migrations/sqlite: full SQLite schema (0001-0005)
- config: Database.Driver field ("postgres" or "sqlite")
- main.go: SQLite connection with WAL mode, single writer
- server/setup: quest check + preset selection steps
- server/api: /dashboard with live stats
- .github/workflows: Docker in release, deduplicate docker.yml

server/migrations/migrations_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/jmoiron/sqlx"
 	_ "github.com/lib/pq"
 	"go.uber.org/zap"
+	_ "modernc.org/sqlite"
 )
 
 func testDB(t *testing.T) *sqlx.DB {
@@ -194,7 +195,7 @@ func TestParseVersion(t *testing.T) {
 }
 
 func TestReadMigrations(t *testing.T) {
-	migrations, err := readMigrations()
+	migrations, err := readMigrations(false)
 	if err != nil {
 		t.Fatalf("readMigrations failed: %v", err)
 	}
@@ -210,7 +211,7 @@ func TestReadMigrations(t *testing.T) {
 }
 
 func TestReadMigrations_Sorted(t *testing.T) {
-	migrations, err := readMigrations()
+	migrations, err := readMigrations(false)
 	if err != nil {
 		t.Fatalf("readMigrations failed: %v", err)
 	}
@@ -223,7 +224,7 @@ func TestReadMigrations_Sorted(t *testing.T) {
 }
 
 func TestReadMigrations_AllHaveSQL(t *testing.T) {
-	migrations, err := readMigrations()
+	migrations, err := readMigrations(false)
 	if err != nil {
 		t.Fatalf("readMigrations failed: %v", err)
 	}
@@ -235,7 +236,7 @@ func TestReadMigrations_AllHaveSQL(t *testing.T) {
 }
 
 func TestReadMigrations_BaselineIsLargest(t *testing.T) {
-	migrations, err := readMigrations()
+	migrations, err := readMigrations(false)
 	if err != nil {
 		t.Fatalf("readMigrations failed: %v", err)
 	}
@@ -252,6 +253,61 @@ func TestReadMigrations_BaselineIsLargest(t *testing.T) {
 	}
 }
 
+func TestReadMigrations_SQLite(t *testing.T) {
+	migrations, err := readMigrations(true)
+	if err != nil {
+		t.Fatalf("readMigrations(sqlite) failed: %v", err)
+	}
+	if len(migrations) != 5 {
+		t.Fatalf("expected 5 SQLite migrations, got %d", len(migrations))
+	}
+	if migrations[0].filename != "0001_init.sql" {
+		t.Errorf("first SQLite migration = %q, want 0001_init.sql", migrations[0].filename)
+	}
+	for _, m := range migrations {
+		if m.sql == "" {
+			t.Errorf("SQLite migration %s has empty SQL", m.filename)
+		}
+	}
+}
+
+func TestSQLiteMigrateInMemory(t *testing.T) {
+	db, err := sqlx.Open("sqlite", ":memory:?_pragma=foreign_keys(1)")
+	if err != nil {
+		t.Fatalf("Failed to open in-memory SQLite: %v", err)
+	}
+	defer func() { _ = db.Close() }()
+
+	logger, _ := zap.NewDevelopment()
+	applied, err := Migrate(db, logger)
+	if err != nil {
+		t.Fatalf("Migrate to SQLite failed: %v", err)
+	}
+	if applied != 5 {
+		t.Errorf("expected 5 migrations applied, got %d", applied)
+	}
+
+	ver, err := Version(db)
+	if err != nil {
+		t.Fatalf("Version failed: %v", err)
+	}
+	if ver != 5 {
+		t.Errorf("expected version 5, got %d", ver)
+	}
+
+	// Verify a few key tables exist
+	for _, table := range []string{"users", "characters", "guilds", "guild_characters", "sign_sessions"} {
+		var count int
+		err := db.QueryRow("SELECT COUNT(*) FROM sqlite_master WHERE type='table' AND name=?", table).Scan(&count)
+		if err != nil {
+			t.Errorf("Failed to check table %s: %v", table, err)
+		}
+		if count != 1 {
+			t.Errorf("Table %s not found in SQLite schema", table)
+		}
+	}
+}
+
 func TestParseVersion_Comprehensive(t *testing.T) {
 	tests := []struct {
 		filename string