chore(deps): point dependabot at dev — main is a mirror of dev

Dependabot targeted the default branch (main), so dep PRs piled up
against the branch nobody integrates on and re-desynced main on merge.

Claude-Session: https://claude.ai/code/session_01NeCAbhQFb9q3jPAw15xToK

Author: volod-vana

.github/dependabot.yml

@@ -2,6 +2,7 @@ version: 2
 updates:
   - package-ecosystem: npm
     directory: "/"
+    target-branch: dev
     schedule:
       interval: weekly
       day: monday
@@ -12,6 +13,7 @@ updates:
 
   - package-ecosystem: github-actions
     directory: "/"
+    target-branch: dev
     schedule:
       interval: weekly
       day: monday