Rename project from TopDeck to Canon

- Module github.com/cdnutter/canon, binary/command cmd/canon, Docker
  image and compose project "canon"
- Environment variables now use the CANON_ prefix
- Default site title is "<Your name>'s Canon" (or "Canon" with no name);
  a Site title set in Settings still overrides it
- Existing topdeck.db (and WAL files) is renamed to canon.db on start
- README: upgrade notes, including moving the old compose volume

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/api.go

@@ -10,10 +10,10 @@ import (
 	"time"
 	"unicode/utf8"
 
-	"github.com/cdnutter/topdeck/internal/auth"
-	"github.com/cdnutter/topdeck/internal/imgcache"
-	"github.com/cdnutter/topdeck/internal/providers"
-	"github.com/cdnutter/topdeck/internal/store"
+	"github.com/cdnutter/canon/internal/auth"
+	"github.com/cdnutter/canon/internal/imgcache"
+	"github.com/cdnutter/canon/internal/providers"
+	"github.com/cdnutter/canon/internal/store"
 )
 
 // ---- lists ----
@@ -466,19 +466,20 @@ func (s *Server) apiSettings(w http.ResponseWriter, r *http.Request) {
 	}
 	u, _ := s.currentUser(r)
 	writeJSON(w, http.StatusOK, map[string]any{
-		"siteTitle":     set[store.SettingSiteTitle],
-		"ownerName":     site.OwnerName,
-		"tagline":       site.Tagline,
-		"avatar":        site.AvatarURL,
-		"theme":         site.Theme,
-		"customCss":     set[store.SettingCustomCSS],
-		"previewCount":  site.PreviewCount,
-		"showNotes":     site.ShowNotes,
-		"musicProvider": orDefault(set[store.SettingMusicProvider], "deezer"),
-		"tvProvider":    orDefault(set[store.SettingTVProvider], "tvdb"),
-		"secrets":       secrets,
-		"themes":        Themes,
-		"username":      u.Username,
+		"siteTitle":      set[store.SettingSiteTitle],
+		"siteTitleShown": site.Title,
+		"ownerName":      site.OwnerName,
+		"tagline":        site.Tagline,
+		"avatar":         site.AvatarURL,
+		"theme":          site.Theme,
+		"customCss":      set[store.SettingCustomCSS],
+		"previewCount":   site.PreviewCount,
+		"showNotes":      site.ShowNotes,
+		"musicProvider":  orDefault(set[store.SettingMusicProvider], "deezer"),
+		"tvProvider":     orDefault(set[store.SettingTVProvider], "tvdb"),
+		"secrets":        secrets,
+		"themes":         Themes,
+		"username":       u.Username,
 	})
 }