feat(handlers): integrate ProgressService into media, koreader, kobo, and queue

All four progress write paths now delegate to ProgressService.SaveProgress:

- MediaHandler: UpdateMediaReadingProgress uses ProgressService for web
  saves with richer request body (reading_mode, zoom_level, scroll). GET
  now uses GetUniversalProgress query that JOINs media_items for
  format_group, total_characters, chapter_count.

- KOReaderHandler: updateProgressForBook delegates to ProgressService.
  Fixed device ID bug (was using userID, now uses deviceID). Removed
  duplicate UpdateDeviceLastSync with zero UUID. Added pgtype helper
  functions (textPtrToPgText, intPtrToPgInt4, int64PtrToPgInt8).

- KoboHandler: all four progress write points (Markup ReadingSync, Markup
  last-read-place, AnalyticsGettests, SyncFromServer) delegate to
  ProgressService. Fixed empty epubcfi string now correctly set to
  Valid: false. SyncFromServer preserves last_sync_source=bookhoard
  and Broadcast: false.

- QueueProcessor: syncProgress delegates to ProgressService.

- main.go: creates ProgressService after ConnectionManager, injects via
  SetProgressService() on all handlers and queue processor.

Handler tests cover pgtype conversion helpers (textPtrToPgText, etc.)
and device icon mapping.

internal/handlers/progress_test.go

@@ -3,6 +3,7 @@ package handlers
 import (
 	"testing"
 
+	"github.com/jackc/pgx/v5/pgtype"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -28,3 +29,124 @@ func TestGetDeviceIcon_Unknown(t *testing.T) {
 	result = getDeviceIcon("")
 	assert.Equal(t, "📚", result)
 }
+
+func TestTextPtrToPgText(t *testing.T) {
+	t.Run("nil returns invalid", func(t *testing.T) {
+		result := textPtrToPgText(nil)
+		assert.False(t, result.Valid)
+	})
+	t.Run("non-nil returns valid", func(t *testing.T) {
+		s := "epubcfi(/6/4/2:10)"
+		result := textPtrToPgText(&s)
+		assert.True(t, result.Valid)
+		assert.Equal(t, s, result.String)
+	})
+	t.Run("empty string returns valid", func(t *testing.T) {
+		s := ""
+		result := textPtrToPgText(&s)
+		assert.True(t, result.Valid)
+		assert.Equal(t, "", result.String)
+	})
+}
+
+func TestIntPtrToPgInt4(t *testing.T) {
+	t.Run("nil returns invalid", func(t *testing.T) {
+		result := intPtrToPgInt4(nil)
+		assert.False(t, result.Valid)
+	})
+	t.Run("non-nil returns valid", func(t *testing.T) {
+		v := 5
+		result := intPtrToPgInt4(&v)
+		assert.True(t, result.Valid)
+		assert.Equal(t, int32(5), result.Int32)
+	})
+}
+
+func TestInt64PtrToPgInt8(t *testing.T) {
+	t.Run("nil returns invalid", func(t *testing.T) {
+		result := int64PtrToPgInt8(nil)
+		assert.False(t, result.Valid)
+	})
+	t.Run("non-nil returns valid", func(t *testing.T) {
+		v := int64(10000)
+		result := int64PtrToPgInt8(&v)
+		assert.True(t, result.Valid)
+		assert.Equal(t, int64(10000), result.Int64)
+	})
+}
+
+func TestFloat64PtrHelpers(t *testing.T) {
+	t.Run("pgtype float64 valid", func(t *testing.T) {
+		v := pgtype.Float8{Float64: 0.5, Valid: true}
+		result := float64PtrVal(v)
+		assert.NotNil(t, result)
+		assert.InDelta(t, 0.5, *result, 0.001)
+	})
+	t.Run("pgtype float64 invalid", func(t *testing.T) {
+		v := pgtype.Float8{Valid: false}
+		result := float64PtrVal(v)
+		assert.Nil(t, result)
+	})
+	t.Run("pgtype text valid", func(t *testing.T) {
+		v := pgtype.Text{String: "hello", Valid: true}
+		result := textPtrVal(v)
+		assert.NotNil(t, result)
+		assert.Equal(t, "hello", *result)
+	})
+	t.Run("pgtype text invalid", func(t *testing.T) {
+		v := pgtype.Text{Valid: false}
+		result := textPtrVal(v)
+		assert.Nil(t, result)
+	})
+	t.Run("pgtype int4 valid", func(t *testing.T) {
+		v := pgtype.Int4{Int32: 42, Valid: true}
+		result := int32PtrVal(v)
+		assert.NotNil(t, result)
+		assert.Equal(t, 42, *result)
+	})
+	t.Run("pgtype int4 invalid", func(t *testing.T) {
+		v := pgtype.Int4{Valid: false}
+		result := int32PtrVal(v)
+		assert.Nil(t, result)
+	})
+	t.Run("pgtype int8 valid", func(t *testing.T) {
+		v := pgtype.Int8{Int64: 10000, Valid: true}
+		result := int64PtrVal(v)
+		assert.NotNil(t, result)
+		assert.Equal(t, int64(10000), *result)
+	})
+	t.Run("pgtype int8 invalid", func(t *testing.T) {
+		v := pgtype.Int8{Valid: false}
+		result := int64PtrVal(v)
+		assert.Nil(t, result)
+	})
+}
+
+func float64PtrVal(v pgtype.Float8) *float64 {
+	if v.Valid {
+		return &v.Float64
+	}
+	return nil
+}
+
+func textPtrVal(v pgtype.Text) *string {
+	if v.Valid {
+		return &v.String
+	}
+	return nil
+}
+
+func int32PtrVal(v pgtype.Int4) *int {
+	if v.Valid {
+		val := int(v.Int32)
+		return &val
+	}
+	return nil
+}
+
+func int64PtrVal(v pgtype.Int8) *int64 {
+	if v.Valid {
+		return &v.Int64
+	}
+	return nil
+}