fix: restore test-used functions, silence tx.Rollback closed errors, prune knip dead code

Restore processImage (images.go) and nonDepositPaymentType (handlers.go) with //nolint:unused — used in test files.
Fix 97 tx.Rollback defers to silently discard expected "tx is closed" error after commit.
Frontend: remove 44 unused shadcn-svelte files, 2 dead components, 9 stale npm deps, prune unused exports.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/handlers/user/profile.go

@@ -318,9 +318,9 @@ func UpdateProfileHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	defer func() {
-		if err := tx.Rollback(r.Context()); err != nil {
-			slog.Error("failed to rollback transaction", "err", err)
-		}
+		if err := tx.Rollback(r.Context()); err != nil && err.Error() != "tx is closed" {
+    slog.Error("failed to rollback transaction", "err", err)
+}
 	}()
 
 	// If first or last name changed (via user edit), track the old names in history
@@ -725,9 +725,9 @@ func ChangePasswordHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	defer func() {
-		if err := tx.Rollback(r.Context()); err != nil {
-			slog.Error("failed to rollback transaction", "err", err)
-		}
+		if err := tx.Rollback(r.Context()); err != nil && err.Error() != "tx is closed" {
+    slog.Error("failed to rollback transaction", "err", err)
+}
 	}()
 
 	_, err = tx.Exec(r.Context(), `UPDATE users SET password_hash = $1, updated_at = NOW() WHERE id = $2`, string(newHash), userID)
@@ -863,9 +863,9 @@ func AddPatchTestHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	defer func() {
-		if err := tx.Rollback(r.Context()); err != nil {
-			slog.Error("failed to rollback transaction", "err", err)
-		}
+		if err := tx.Rollback(r.Context()); err != nil && err.Error() != "tx is closed" {
+    slog.Error("failed to rollback transaction", "err", err)
+}
 	}()
 
 	_, err = tx.Exec(r.Context(), `
@@ -958,9 +958,9 @@ func DeletePatchTestHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	defer func() {
-		if err := tx.Rollback(r.Context()); err != nil {
-			slog.Error("failed to rollback transaction", "err", err)
-		}
+		if err := tx.Rollback(r.Context()); err != nil && err.Error() != "tx is closed" {
+    slog.Error("failed to rollback transaction", "err", err)
+}
 	}()
 
 	result, err := tx.Exec(r.Context(), `
@@ -1064,9 +1064,9 @@ func UploadProfilePictureHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	defer func() {
-		if err := tx.Rollback(r.Context()); err != nil {
-			slog.Error("failed to rollback transaction", "err", err)
-		}
+		if err := tx.Rollback(r.Context()); err != nil && err.Error() != "tx is closed" {
+    slog.Error("failed to rollback transaction", "err", err)
+}
 	}()
 
 	_, err = tx.Exec(r.Context(), `UPDATE users SET profile_pic_url = $1 WHERE id = $2`, url, userID)
@@ -1185,9 +1185,9 @@ func UpdateNotificationPreferencesHandler(w http.ResponseWriter, r *http.Request
 		return
 	}
 	defer func() {
-		if err := tx.Rollback(r.Context()); err != nil {
-			slog.Error("failed to rollback transaction", "err", err)
-		}
+		if err := tx.Rollback(r.Context()); err != nil && err.Error() != "tx is closed" {
+    slog.Error("failed to rollback transaction", "err", err)
+}
 	}()
 
 	if exists {