Remove Dependabot and auto-update workflows

Manual dependency management is simpler and gives more control.

.claude/settings.local.json

@@ -25,7 +25,8 @@
       "Bash(Select-String -Pattern \"Checking|Finished|error\")",
       "Bash(Select-Object -First 20)",
       "Bash(git restore:*)",
-      "Bash(test:*)"
+      "Bash(test:*)",
+      "Bash(gh pr list:*)"
     ],
     "deny": [],
     "ask": []