feat(security): add CSRF protection for all state-changing API routes

- Synchronizer token stored in session; GET /auth/csrf to obtain it
- csrfProtection middleware requires X-CSRF-Token on non-safe methods
- customFetch injects the header via setCsrfTokenGetter
- toolrate boot loads token; reload after local login (session regenerate)
- OpenAPI GET /auth/csrf + CsrfToken schema, orval regenerated

lib/api-spec/openapi.yaml

@@ -570,6 +570,19 @@ paths:
               schema:
                 $ref: "#/components/schemas/AuthMode"
 
+  /auth/csrf:
+    get:
+      operationId: getCsrfToken
+      tags: [auth]
+      summary: Get a CSRF token for state-changing requests
+      responses:
+        "200":
+          description: CSRF token
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/CsrfToken"
+
   /auth/login:
     post:
       operationId: localLogin
@@ -942,6 +955,13 @@ components:
           type: string
           enum: [oidc, local]
 
+    CsrfToken:
+      type: object
+      required: [token]
+      properties:
+        token:
+          type: string
+
     LocalLoginInput:
       type: object
       required: [username, password]