chore: add 7-day cooldown to all dependabot entries

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dguido

.github/dependabot.yml

@@ -4,6 +4,8 @@ updates:
     directory: "/backend"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     groups:
       all-deps:
         patterns:
@@ -13,6 +15,8 @@ updates:
     directory: "/content-server"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     groups:
       all-deps:
         patterns:
@@ -22,6 +26,8 @@ updates:
     directory: "/frontend"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     groups:
       all-deps:
         patterns:
@@ -31,6 +37,8 @@ updates:
     directory: "/backend"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     groups:
       all-deps:
         patterns:
@@ -40,6 +48,8 @@ updates:
     directory: "/content-server"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     groups:
       all-deps:
         patterns:
@@ -49,6 +59,8 @@ updates:
     directory: "/frontend"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7
     groups:
       all-deps:
         patterns: