Add project scaffolding with fx DI, SQLite migrations, and healthcheck

- go.mod with git.eeqj.de/sneak/chat module
- internal packages: globals, logger, config, db, healthcheck, middleware, handlers, server
- SQLite database with embedded migration system (schema_migrations tracking)
- Migration 001: schema_migrations table
- Migration 002: channels table
- Config with chat-specific vars (MAX_HISTORY, SESSION_TIMEOUT, MAX_MESSAGE_SIZE, MOTD, SERVER_NAME, FEDERATION_KEY)
- Healthcheck endpoint at /.well-known/healthcheck.json
- Makefile, .gitignore
- cmd/chatd/main.go entry point

internal/globals/globals.go

@@ -0,0 +1,23 @@
+package globals
+
+import (
+	"go.uber.org/fx"
+)
+
+var (
+	Appname string
+	Version string
+)
+
+type Globals struct {
+	Appname string
+	Version string
+}
+
+func New(lc fx.Lifecycle) (*Globals, error) {
+	n := &Globals{
+		Appname: Appname,
+		Version: Version,
+	}
+	return n, nil
+}