Add admin config page and runtime-tunable upload/rate-limit settings

internal/config/model.go

@@ -0,0 +1,21 @@
+package config
+
+import "time"
+
+// ConfigEntry stores runtime-tunable configuration in the database.
+// Values are stored as strings but helpers exist for ints/bools/durations.
+//
+// NOTE: keep keys stable; they are effectively part of the public admin surface.
+//
+// Example keys:
+// - upload.max_file_size_bytes
+// - upload.multi.max_files
+// - upload.max_hours
+// - ratelimit.login.per_minute
+// - ratelimit.api.per_minute
+//
+type ConfigEntry struct {
+	Key       string `gorm:"primaryKey;size:128"`
+	Value     string `gorm:"size:2048"`
+	UpdatedAt time.Time
+}