refactor(repo): consolidate openflare-server to root and move subprojects to internal/apps

- Merge all files inside openflare-server to the repository root directory.
- Relocate agent, relay, and flared subprojects from internal/ to internal/apps/.
- Combine docker-compose files and update build context paths to root.
- Update GitHub workflows and Dockerfiles to refer to new directories and package names.
- Rewrite Go package imports across all files.
- Resolve database renew test race condition and clean up docs.

internal/apps/upload/ingest/errors.go

@@ -0,0 +1,16 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package ingest
+
+import (
+	"errors"
+
+	"github.com/Rain-kl/Wavelet/internal/apps/upload/shared"
+)
+
+// ErrForbidden indicates the caller is not allowed to mutate the upload record.
+var ErrForbidden = errors.New("upload forbidden")
+
+// ErrStorageReadOnly indicates the storage backend is in migration read-only mode.
+var ErrStorageReadOnly = errors.New(shared.ErrStorageReadOnly)