Add file visibility (PRIVATE/PUBLIC) + public files API

Adds a visibility enum to files with PRIVATE (default) and PUBLIC states.
PUBLIC files are accessible via an unauthenticated /api/files/v1/{fileID}
endpoint that redirects to a presigned S3 URL. Introduces pkg/file service
to manage file operations. Logo uploads (trust centers, organizations,
frameworks, references) are marked PUBLIC; other files are PRIVATE.
Includes database migration and backfill for existing logos.

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/file/service.go

@@ -0,0 +1,67 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package file
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"go.gearno.de/kit/pg"
+	"go.probo.inc/probo/pkg/coredata"
+	"go.probo.inc/probo/pkg/filemanager"
+	"go.probo.inc/probo/pkg/gid"
+)
+
+type Service struct {
+	pg          *pg.Client
+	fileManager *filemanager.Service
+}
+
+func NewService(pgClient *pg.Client, fileManager *filemanager.Service) *Service {
+	return &Service{
+		pg:          pgClient,
+		fileManager: fileManager,
+	}
+}
+
+func (s *Service) GetPublicFileURL(
+	ctx context.Context,
+	fileID gid.GID,
+	expiresIn time.Duration,
+) (string, error) {
+	file := &coredata.File{}
+
+	err := s.pg.WithConn(
+		ctx,
+		func(conn pg.Conn) error {
+			if err := file.LoadPublicByID(ctx, conn, fileID); err != nil {
+				return fmt.Errorf("cannot load public file: %w", err)
+			}
+
+			return nil
+		},
+	)
+	if err != nil {
+		return "", err
+	}
+
+	presignedURL, err := s.fileManager.GenerateFileUrl(ctx, file, expiresIn)
+	if err != nil {
+		return "", fmt.Errorf("cannot generate file URL: %w", err)
+	}
+
+	return presignedURL, nil
+}