docs(api): add universal progress tracking documentation

- get_universal_progress.md - GET /api/progress/:id
- update_universal_progress.md - POST /api/progress/:id
- get_progress_history.md - GET /api/progress/:id/history

Documents device-agnostic (universal) reading progress tracking
that works across all devices (Kobo, KOReader, etc.)

docs/developer/api/book-matching/delete_device_file_alias.md

@@ -0,0 +1,41 @@
+# Delete Device File Alias
+
+Delete a device file alias.
+
+**Endpoint**: `DELETE /api/devices/:id/file-aliases/:aliasId`
+**Auth**: Required
+
+## Path Parameters
+
+| Parameter | Type | Required | Description |
+|-----------|------|-----------|-------------|
+| id | string (UUID) | Yes | Device UUID |
+| aliasId | string (UUID) | Yes | File alias UUID |
+
+## Request Headers
+
+| Header | Type | Required | Description |
+|--------|------|-----------|-------------|
+| Authorization | string | Yes | Bearer token |
+
+### Example Request
+
+```http
+DELETE /api/devices/550e8400-e29b-41d4-a716-446655440000/file-aliases/660e8400-e29b-41d4-a716-446655440001
+Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
+```
+
+## Response (204 No Content)
+
+File alias deleted successfully.
+
+## Error Responses
+
+| Code | Description |
+|------|-------------|
+| 401 | Invalid or expired token |
+| 404 | Device or file alias not found |
+
+## Try It Out
+
+<!-- API Explorer will be inserted here in Phase 3 -->