feat: implement update-service v1 migration and enrollment flow

- added /update/enroll endpoint and enrollment logic
- migrated update client to v1 api endpoints and bearer auth
- implemented remote status reporting in backend and scripts
- updated requirements and project status

docs/architecture/openapi/paths/enroll.yaml

@@ -0,0 +1,65 @@
+post:
+  summary: Enroll client and issue long-term token
+  security: []
+  requestBody:
+    required: true
+    content:
+      application/json:
+        schema:
+          $ref: '../schemas/enroll-request.yaml'
+        examples:
+          enroll:
+            value:
+              project_id: demo
+              client_id: device-42
+              software_id: kiosk
+              enroll_token: enroll_6f3d2c...
+  responses:
+    '200':
+      description: Enrollment successful
+      content:
+        application/json:
+          schema:
+            $ref: '../schemas/enroll-response.yaml'
+          examples:
+            issued:
+              value:
+                token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
+                scope: read_manifest report_status
+                expires_at: 2026-12-30T10:00:00Z
+    '400':
+      description: Bad Request
+      x-error-codes: [invalid_payload]
+      content:
+        application/json:
+          schema:
+            $ref: '../schemas/error.yaml'
+          examples:
+            invalid_payload:
+              value:
+                code: invalid_payload
+                message: Missing required fields
+    '401':
+      description: Unauthorized
+      x-error-codes: [unauthorized]
+      content:
+        application/json:
+          schema:
+            $ref: '../schemas/error.yaml'
+          examples:
+            unauthorized:
+              value:
+                code: unauthorized
+                message: Invalid or expired enrollment token
+    '409':
+      description: Conflict
+      x-error-codes: [already_enrolled]
+      content:
+        application/json:
+          schema:
+            $ref: '../schemas/error.yaml'
+          examples:
+            already_enrolled:
+              value:
+                code: already_enrolled
+                message: Client already enrolled