chore(mcp): rename mai → supabase in .mcp.json

Project-scope `mai` server collided with the user-scope maimcp
orchestration binary registered in ~/.claude.json — silently rebinding
mcp__mai__* from list_tasks/update_task/send_message to Supabase SQL
tools. Renaming to `supabase` keeps the namespaces disjoint.

Refs: m/mAi#154

.mcp.json

@@ -1,6 +1,6 @@
 {
   "mcpServers": {
-    "mai": {
+    "supabase": {
       "type": "http",
       "url": "http://100.99.98.201:8000/mcp",
       "headers": {