fix: resolve all lint errors and make linting a required CI check (#62)

- Fix 10 err113 violations: extract dynamic errors to package-level sentinels
- Fix 12 errcheck violations: handle unchecked error returns in player,
  metadata, and config packages
- Fix 4 revive stutter warnings: rename player.PlayerState to player.State,
  player.PlayerVolume to player.Volume, queue.QueueTrack to queue.Track,
  queue.QueueState to queue.State
- Fix 2 staticcheck SA4001: simplify *&x to x in assets handler
- Fix 5 unused constants: remove dead AudioFileType iota block in models
- Fix gci/gofumpt/wsl formatting issues across multiple files
- Add gofumpt module-path setting to .golangci.yml for correct import grouping
- Fix player test: gate integration test behind YELLOWJACKET_INTEGRATION env var
  instead of only skipping in CI, and replace t.Errorf+t.Failed with t.Fatalf
- Remove continue-on-error from golangci-lint CI step so linting is now required

backend/config/config.go

@@ -11,6 +11,7 @@ import (
 	"path"
 
 	"github.com/BurntSushi/toml"
+
 	"yellowjacket/backend/library"
 	"yellowjacket/backend/system"
 )

backend/config/httphandler.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/gorilla/schema"
 	"github.com/wailsapp/wails/v2/pkg/runtime"
+
 	"yellowjacket/backend/events"
 )
 
@@ -27,13 +28,20 @@ func (c *Config) handle(w http.ResponseWriter, r *http.Request) {
 	case http.MethodPost:
 		if err := c.handleConfigPost(r); err != nil {
 			c.logger.Error("problem handling config post request", "err", err.Error())
-			c.formSubmitError(err.Error()).Render(r.Context(), w)
+
+			if renderErr := c.formSubmitError(err.Error()).Render(r.Context(), w); renderErr != nil {
+				c.logger.Error("problem rendering error response", "err", renderErr.Error())
+			}
+
 			w.WriteHeader(http.StatusInternalServerError)
 
 			return
 		}
 
-		c.formSubmitSuccess().Render(r.Context(), w)
+		if err := c.formSubmitSuccess().Render(r.Context(), w); err != nil {
+			c.logger.Error("problem rendering success response", "err", err.Error())
+		}
+
 		w.WriteHeader(http.StatusOK)
 	}
 }