refactor: remove obsolete resource download and installer endpoints

- Deleted the `POST /resources/get/{dataFolder?}` and `GET /resources/get-installer` endpoints as part of the architectural shift towards simplified resource management.
- Removed associated methods and configurations, including `ResourcesService.GetEncryptedResource`, `ResourcesService.GetInstaller`, and related properties in `ResourcesConfig`.
- Cleaned up environment variables and configuration files to reflect the removal of installer-related settings.
- Eliminated the `GetResourceRequest` DTO and its validator, along with the `WrongResourceName` error code.
- Updated documentation to clarify the changes in resource handling and the retirement of per-user file encryption.

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/02_document/diagrams/flows/flow_encrypted_resource_download.md

@@ -1,29 +1,14 @@
-# Flow: Encrypted Resource Download
+# Flow: Encrypted Resource Download — OBSOLETE
+
+> **Removed in cycle 2 (2026-05-14).**
+>
+> The `POST /resources/get/{dataFolder?}` endpoint, the `ResourcesService.GetEncryptedResource` method, the `Security.GetApiEncryptionKey` / `EncryptTo` / `DecryptTo` helpers, the `GetResourceRequest` DTO + validator, and the `ExceptionEnum.WrongResourceName` (50) error code no longer exist. Per-user file encryption is no longer part of the system; resource files are stored as plain bytes and only ever leave the server through upload (`POST /resources/{dataFolder?}`) and admin clear (`POST /resources/clear/{dataFolder?}`).
+>
+> See `_docs/02_document/architecture.md` ADR-003 (retired) and `_docs/02_document/system-flows.md` flow F3 (removed) for context.
+>
+> This file is retained as a tombstone so historical references resolve. Do not link to it from new docs.
 
 ```mermaid
-sequenceDiagram
-    participant Client
-    participant API as Admin API
-    participant Auth as AuthService
-    participant US as UserService
-    participant Sec as Security
-    participant RS as ResourcesService
-    participant FS as Filesystem
-
-    Client->>API: POST /resources/get {password, hardware, fileName}
-    API->>Auth: GetCurrentUser()
-    Auth-->>API: User
-    API->>US: CheckHardwareHash(user, hardware)
-    US->>Sec: GetHWHash(hardware)
-    Sec-->>US: hash
-    US-->>API: hwHash
-    API->>Sec: GetApiEncryptionKey(email, password, hwHash)
-    Sec-->>API: AES key
-    API->>RS: GetEncryptedResource(folder, fileName, key)
-    RS->>FS: Read file
-    FS-->>RS: FileStream
-    RS->>Sec: EncryptTo(stream, key) [AES-256-CBC]
-    Sec-->>RS: Encrypted MemoryStream
-    RS-->>API: Stream
-    API-->>Client: 200 OK (application/octet-stream)
+flowchart TD
+    Start([POST /resources/get — REMOVED]) --> Removed[Endpoint deleted in cycle 2]
 ```