test: remove dead Spectron integration suite + jest artifacts (D.4)

- Delete integration-tests/ (Spectron, incompatible with Electron 42),
  config/jest/, scripts/test.js, docker-compose.yml (all integration-only).
- Add ESLint override exposing Vitest globals (vi/describe/it/...) for test
  and __mocks__ files.
Jest is fully removed; Vitest is the sole test runner.

Author: jthrilly

.eslintrc.json

@@ -139,5 +139,22 @@
              "minLength": 3
          }
      ]
-    }
+    },
+    "overrides": [
+      {
+        "files": ["**/*.test.js", "**/__tests__/**", "**/__mocks__/**", "vitest.setup.js"],
+        "globals": {
+          "vi": "readonly",
+          "describe": "readonly",
+          "it": "readonly",
+          "test": "readonly",
+          "expect": "readonly",
+          "beforeAll": "readonly",
+          "afterAll": "readonly",
+          "beforeEach": "readonly",
+          "afterEach": "readonly",
+          "vitest": "readonly"
+        }
+      }
+    ]
 }