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/discordbot/discord_bot_test.go

@@ -12,18 +12,18 @@ import (
 
 // mockSession implements the Session interface for testing.
 type mockSession struct {
-	openErr                error
-	channelResult          *discordgo.Channel
-	channelErr             error
-	userResults            map[string]*discordgo.User
-	userErr                error
-	messageSentTo          string
-	messageSentContent     string
-	messageErr             error
-	addHandlerCalls        int
-	bulkOverwriteAppID     string
-	bulkOverwriteCommands  []*discordgo.ApplicationCommand
-	bulkOverwriteErr       error
+	openErr               error
+	channelResult         *discordgo.Channel
+	channelErr            error
+	userResults           map[string]*discordgo.User
+	userErr               error
+	messageSentTo         string
+	messageSentContent    string
+	messageErr            error
+	addHandlerCalls       int
+	bulkOverwriteAppID    string
+	bulkOverwriteCommands []*discordgo.ApplicationCommand
+	bulkOverwriteErr      error
 }
 
 func (m *mockSession) Open() error {