chore(misc): improve Renovate configuration with PR method and smart dependency grouping (#2457)

* chore(renovate): switch from automergeBranch to automergePr method

This change switches Renovate from using the branch method to the PR method for automerging. The PR method is Renovate's fallback method anyway, so there will be no functional change, but it will help avoid errors that are currently added as comments to each PR.

* chore(renovate): add package manager grouping configuration

Group dependencies by package manager to reduce PR noise:
- Python pip dependencies grouped as 'Python dependencies'
- GitHub Actions dependencies grouped as 'GitHub Actions'
- Docker dependencies grouped as 'Docker dependencies'

This will create fewer, more focused PRs instead of individual updates for each dependency.

* chore(renovate): refine grouping to separate major updates

Separate major and non-major updates for each package manager:
- Non-major updates (minor/patch/pin/digest) are grouped together and eligible for automerge via existing presets
- Major updates are grouped separately and explicitly disable automerge for manual review
- This ensures major version changes require human oversight while allowing safe updates to be automated

.github/renovate.json

@@ -3,7 +3,7 @@
   "extends": [
     "config:best-practices",
     "customManagers:githubActionsVersions",
-    ":automergeBranch",
+    ":automergePr",
     ":automergeDigest",
     ":automergeLinters",
     ":automergeStableNonMajor",
@@ -17,5 +17,52 @@
   ],
   "ignorePaths": [
     "includes/docker/docker-compose.yml"
+  ],
+  "packageRules": [
+    {
+      "description": "Group Python non-major dependencies",
+      "matchManagers": ["pip_requirements"],
+      "matchUpdateTypes": ["minor", "patch", "pin", "digest"],
+      "groupName": "Python dependencies",
+      "groupSlug": "python-deps"
+    },
+    {
+      "description": "Group Python major dependencies",
+      "matchManagers": ["pip_requirements"],
+      "matchUpdateTypes": ["major"],
+      "groupName": "Python major dependencies",
+      "groupSlug": "python-major",
+      "automerge": false
+    },
+    {
+      "description": "Group GitHub Actions non-major dependencies",
+      "matchManagers": ["github-actions"],
+      "matchUpdateTypes": ["minor", "patch", "pin", "digest"],
+      "groupName": "GitHub Actions",
+      "groupSlug": "github-actions"
+    },
+    {
+      "description": "Group GitHub Actions major dependencies",
+      "matchManagers": ["github-actions"],
+      "matchUpdateTypes": ["major"],
+      "groupName": "GitHub Actions major",
+      "groupSlug": "github-actions-major",
+      "automerge": false
+    },
+    {
+      "description": "Group Docker non-major dependencies",
+      "matchManagers": ["docker-compose", "dockerfile"],
+      "matchUpdateTypes": ["minor", "patch", "pin", "digest"],
+      "groupName": "Docker dependencies",
+      "groupSlug": "docker-deps"
+    },
+    {
+      "description": "Group Docker major dependencies",
+      "matchManagers": ["docker-compose", "dockerfile"],
+      "matchUpdateTypes": ["major"],
+      "groupName": "Docker major dependencies",
+      "groupSlug": "docker-major",
+      "automerge": false
+    }
   ]
 }