Shared Renovate preset for every Bennett app

The rules were copied into each app's renovate.json, so they were identical only by luck
and a change meant six edits — the Testcontainers guard existed in two repos and not the
other four. Apps now extend this.

Also records the two majors that are blocked upstream rather than by our code:
typescript-eslint peers at typescript <6.1, eslint-plugin-react peers at eslint <=9.7.

default.json

@@ -0,0 +1,34 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "description": "Shared preset for every app on the Bennett platform. Apps extend this rather than copying rules, so a change here reaches all of them.",
+  "extends": ["config:recommended"],
+  "packageRules": [
+    {
+      "description": "Bennett platform releases: our own code, already tested and Trivy-scanned before publish. Grouped into one PR and merged automatically so a fix reaches every app without manual work. Merging main triggers the build, which re-runs tests and re-scans; if either fails no image is pushed, so a bad bump cannot reach production.",
+      "matchPackageNames": ["net.thebennett.platform:**"],
+      "groupName": "bennett platform",
+      "automerge": true
+    },
+    {
+      "description": "Stay on Testcontainers 1.x. 2.0 renamed the module artifacts (postgresql, junit-jupiter), so the major bump does not just fail the build — its POM will not parse.",
+      "matchPackageNames": ["org.testcontainers:**"],
+      "matchUpdateTypes": ["major"],
+      "enabled": false
+    },
+    {
+      "description": "TypeScript 7 is gated by typescript-eslint, which peers at <6.1. Re-enable once it ships support; until then the PR only ever conflicts with itself.",
+      "matchPackageNames": ["typescript"],
+      "matchUpdateTypes": ["major"],
+      "enabled": false
+    },
+    {
+      "description": "ESLint 10 is gated by eslint-plugin-react, which peers at <=9.7.",
+      "matchPackageNames": ["eslint"],
+      "matchUpdateTypes": ["major"],
+      "enabled": false
+    }
+  ],
+  "vulnerabilityAlerts": {
+    "labels": ["security"]
+  }
+}