chore(deps): add dependabot groups to batch patch/minor bumps per ecosystem

Groups patch and minor updates into a single weekly PR per ecosystem so the
backlog doesn't accumulate dozens of individual bump PRs. Major-version bumps
are intentionally excluded from every group so they still surface as individual
PRs and get deliberate review (e.g. TypeScript 5→6, Vite 7→8).

Applies to: pip (backend), npm (frontend), docker, github-actions.

Author: bg-playground

.github/dependabot.yml

@@ -12,6 +12,13 @@ updates:
     commit-message:
       prefix: "chore(deps)"
     open-pull-requests-limit: 10
+    groups:
+      python-patch-minor:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   # NPM dependencies (frontend)
   - package-ecosystem: "npm"
@@ -25,6 +32,13 @@ updates:
     commit-message:
       prefix: "chore(deps)"
     open-pull-requests-limit: 10
+    groups:
+      npm-patch-minor:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   # Docker dependencies
   - package-ecosystem: "docker"
@@ -38,6 +52,13 @@ updates:
     commit-message:
       prefix: "chore(deps)"
     open-pull-requests-limit: 10
+    groups:
+      docker-patch-minor:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"
 
   # GitHub Actions
   - package-ecosystem: "github-actions"
@@ -51,3 +72,10 @@ updates:
     commit-message:
       prefix: "chore(ci)"
     open-pull-requests-limit: 10
+    groups:
+      actions-patch-minor:
+        patterns:
+          - "*"
+        update-types:
+          - "minor"
+          - "patch"