⬆️(backend) upgrade docspec to v3.0.0 and adapt converter API

Summary

- Bump docspec Docker image from `2.6.3` to `3.0.0` and adapt
`DocSpecConverter` to the new API (raw body upload with explicit
`Content-Type`/`Accept` headers instead of multipart form)

Important

**The Docker image (`ghcr.io/docspecio/api:3.0.0`) must be updated
alongside the code changes.** The new request format is incompatible
with v2.x — deploying only the code without updating the image (or vice
versa) will break document conversion.

compose.yml

@@ -29,8 +29,8 @@ services:
       - MINIO_ROOT_USER=impress
       - MINIO_ROOT_PASSWORD=password
     ports:
-      - '9000:9000'
-      - '9001:9001'
+      - "9000:9000"
+      - "9001:9001"
     healthcheck:
       test: ["CMD", "mc", "ready", "local"]
       interval: 1s
@@ -81,16 +81,16 @@ services:
       - ./src/backend:/app
       - ./data/static:/data/static
     depends_on:
-        postgresql:
-            condition: service_healthy
-            restart: true
-        mailcatcher:
-          condition: service_started
-        redis:
-          condition: service_started
-        createbuckets:
-          condition: service_started
-  
+      postgresql:
+        condition: service_healthy
+        restart: true
+      mailcatcher:
+        condition: service_started
+      redis:
+        condition: service_started
+      createbuckets:
+        condition: service_started
+
   celery-dev:
     user: ${DOCKER_USER:-1000}
     image: impress:backend-development
@@ -143,7 +143,7 @@ services:
 
   frontend-development:
     user: "${DOCKER_USER:-1000}"
-    build: 
+    build:
       context: .
       dockerfile: ./src/frontend/Dockerfile
       target: impress-dev
@@ -173,13 +173,13 @@ services:
     image: node:22
     user: "${DOCKER_USER:-1000}"
     environment:
-      HOME: /tmp 
+      HOME: /tmp
     volumes:
       - ".:/app"
 
   y-provider-development:
     user: ${DOCKER_USER:-1000}
-    build: 
+    build:
       context: .
       dockerfile: ./src/frontend/servers/y-provider/Dockerfile
       target: y-provider-development
@@ -221,7 +221,11 @@ services:
       - --health-enabled=true
       - --metrics-enabled=true
     healthcheck:
-      test: ['CMD-SHELL', 'exec 3<>/dev/tcp/localhost/9000; echo -e "GET /health/live HTTP/1.1\r\nHost: localhost\r\nConnection: close\r\n\r\n" >&3; grep "HTTP/1.1 200 OK" <&3']
+      test:
+        [
+          "CMD-SHELL",
+          'exec 3<>/dev/tcp/localhost/9000; echo -e "GET /health/live HTTP/1.1\r\nHost: localhost\r\nConnection: close\r\n\r\n" >&3; grep "HTTP/1.1 200 OK" <&3',
+        ]
       start_period: 5s
       interval: 1s
       timeout: 2s
@@ -235,7 +239,7 @@ services:
       KC_DB_PASSWORD: pass
       KC_DB_USERNAME: impress
       KC_DB_SCHEMA: public
-      PROXY_ADDRESS_FORWARDING: 'true'
+      PROXY_ADDRESS_FORWARDING: "true"
     ports:
       - "8080:8080"
     depends_on:
@@ -244,7 +248,7 @@ services:
         restart: true
 
   docspec:
-    image: ghcr.io/docspecio/api:2.6.3
+    image: ghcr.io/docspecio/api:3.0.1
     ports:
       - "4000:4000"