fix: address code review findings

- Honor ignore_singles/ignore_compilations at scanner read time so toggles
  take effect immediately on the dashboard, artist page, and digest instead
  of waiting for the MusicBrainz cache to expire and prune rows.
- Run notifier notify synchronously in the scheduler loop to avoid overlapping
  read-send-mark runs double-sending the digest.
- Show artist name (with ID fallback) on the archive page instead of raw IDs.
- Select last_synced in GetAllArtistSettings for contract consistency.
- Fix stale startPeriodicSync comment and remove redundant error var.
- Remove dead ignored-branch from the artist template (never rendered).
- Add tests: CSRF sameOrigin, ArtistCacheFresh, secondary_types round-trip,
  and scanner type-toggle filtering.
- Update Specification.md schema/config to reflect mbid, last_synced,
  secondary_types, sync.interval, and server.public_url.

internal/scanner/scanner_test.go

@@ -202,7 +202,7 @@ func TestFindMissingReleases(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got := FindMissingReleases(tt.local, tt.external, threshold)
+			got := FindMissingReleases(tt.local, tt.external, threshold, TypeFilter{})
 
 			gotRGIDs := make([]string, 0, len(got))
 			for _, m := range got {
@@ -225,6 +225,67 @@ func TestFindMissingReleases(t *testing.T) {
 	}
 }
 
+func TestFindMissingReleases_TypeFilter(t *testing.T) {
+	const threshold = 0.85
+	artist := "artist-a"
+
+	external := []database.ExternalRelease{
+		{RGID: "rg-album", ArtistID: artist, Title: "The Wall", Type: "Album"},
+		{RGID: "rg-single", ArtistID: artist, Title: "B-side", Type: "Single"},
+		{RGID: "rg-comp", ArtistID: artist, Title: "Hits", Type: "Compilation"},
+		{RGID: "rg-comp-sec", ArtistID: artist, Title: "Live at X", Type: "Album", SecondaryTypes: []string{"Compilation"}},
+	}
+
+	tests := []struct {
+		name   string
+		filter TypeFilter
+		want   []string
+	}{
+		{
+			name:   "no filter reports all",
+			filter: TypeFilter{},
+			want:   []string{"rg-album", "rg-single", "rg-comp", "rg-comp-sec"},
+		},
+		{
+			name:   "ignore singles drops Single primary type",
+			filter: TypeFilter{IgnoreSingles: true},
+			want:   []string{"rg-album", "rg-comp", "rg-comp-sec"},
+		},
+		{
+			name:   "ignore compilations drops Compilation primary and secondary type",
+			filter: TypeFilter{IgnoreCompilations: true},
+			want:   []string{"rg-album", "rg-single"},
+		},
+		{
+			name:   "both toggles drop singles and compilations",
+			filter: TypeFilter{IgnoreSingles: true, IgnoreCompilations: true},
+			want:   []string{"rg-album"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := FindMissingReleases(nil, external, threshold, tt.filter)
+			gotRGIDs := make([]string, 0, len(got))
+			for _, m := range got {
+				gotRGIDs = append(gotRGIDs, m.RGID)
+			}
+			wantSet := make(map[string]struct{}, len(tt.want))
+			for _, r := range tt.want {
+				wantSet[r] = struct{}{}
+			}
+			if len(gotRGIDs) != len(tt.want) {
+				t.Fatalf("got %v, want %v", gotRGIDs, tt.want)
+			}
+			for _, r := range gotRGIDs {
+				if _, ok := wantSet[r]; !ok {
+					t.Errorf("unexpected RGID %q", r)
+				}
+			}
+		})
+	}
+}
+
 func TestFindMissingReleases_ThresholdBoundaryInclusive(t *testing.T) {
 	// A title at exactly the threshold must NOT be reported as missing
 	// (IsMatch uses >= threshold).
@@ -240,7 +301,7 @@ func TestFindMissingReleases_ThresholdBoundaryInclusive(t *testing.T) {
 	}
 	// With default threshold 0.85, "The Wall Live" does not match "The Wall";
 	// at a low threshold it would. Confirms threshold is honoured.
-	if len(FindMissingReleases(local, external, 0.85)) != 1 {
+	if len(FindMissingReleases(local, external, 0.85, TypeFilter{})) != 1 {
 		t.Errorf("expected 1 missing at 0.85 threshold")
 	}
 }