chore(claude): harden main-branch guard and gate claude.ai MCP tools (#9248)

- guard-main-branch.sh: exit 2 on block (was advisory echo), and block
  force-push to main from any branch (--force, -f, --force-with-lease, +ref)
- settings.json: gate claude.ai MCP connectors (Stripe, Gmail, Calendar,
  Drive, Slack, Linear) behind permissions.ask

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude/hooks/guard-main-branch.sh

@@ -16,6 +16,23 @@ command="$(echo "$input" | jq -r '.tool_input.command // empty')"
 if [[ "$command" =~ ^git\ (push|reset|revert|checkout|merge|rebase|commit|add) ]]; then
   branch="$(git rev-parse --abbrev-ref HEAD 2>/dev/null || true)"
   if [[ "$branch" == "main" ]]; then
-    echo "BLOCK: You are on the main branch. Create or switch to a feature branch first."
+    echo "BLOCK: You are on the main branch. Create or switch to a feature branch first." >&2
+    exit 2
+  fi
+fi
+
+# Block force-push targeting main from any branch.
+if [[ "$command" =~ ^git[[:space:]]+push([[:space:]]|$) ]]; then
+  has_force=false
+  if [[ "$command" =~ (--force([[:space:]]|=|$)|--force-with-lease|[[:space:]]-f([[:space:]]|$)) ]]; then
+    has_force=true
+  fi
+  # `+ref` refspec syntax is also a force push.
+  if [[ "$command" =~ [[:space:]]\+[A-Za-z] ]]; then
+    has_force=true
+  fi
+  if $has_force && [[ "$command" =~ (^|[[:space:]:])\+?main([[:space:]]|$) ]]; then
+    echo "BLOCK: Force-push to main is not allowed via Claude. Run it yourself if you really mean to." >&2
+    exit 2
   fi
 fi

.claude/settings.json

@@ -72,7 +72,13 @@
       "Bash(chown:*)",
       "Bash(truncate:*)",
       "Bash(shred:*)",
-      "Bash(unlink:*)"
+      "Bash(unlink:*)",
+      "mcp__claude_ai_Stripe",
+      "mcp__claude_ai_Gmail",
+      "mcp__claude_ai_Google_Calendar",
+      "mcp__claude_ai_Google_Drive",
+      "mcp__claude_ai_Slack",
+      "mcp__claude_ai_Linear"
     ]
   },
   "enableAllProjectMcpServers": true,