fix(stats): unblock deploy and register /stats in Telegram command menu

- Remove ReservedConcurrentExecutions: 1 (account lacks unreserved
  concurrency headroom; deploy rolled back). Accept best-effort
  counter semantics as documented.
- Add /stats to aws/telegram-commands.json so it appears in the
  Telegram client's / autocomplete after the next deploy.

aws/telegram-commands.json

@@ -91,6 +91,10 @@
     {
       "command": "trade_stats",
       "description": "Show portfolio summary with P&L"
+    },
+    {
+      "command": "stats",
+      "description": "Show command usage statistics"
     }
   ]
 }

internal/modules/stats/stats.go

@@ -31,7 +31,9 @@ type counter struct {
 func countKey(name string) string { return countPrefix + name }
 
 // Inc increments the persistent invocation count for the named command.
-// Errors are logged and swallowed — stats are best-effort.
+// Errors are logged and swallowed and concurrent invocations of the same
+// command may lose updates — stats are best-effort. A future atomic
+// increment (e.g. DynamoDB UpdateItem ADD) would close the race.
 func (c *counter) Inc(ctx context.Context, name string) {
 	key := countKey(name)
 	var entry countEntry

template.yaml

@@ -135,8 +135,6 @@ Resources:
           TELEGRAM_WEBHOOK_SECRET_PARAMETER_NAME: !Sub "/miti99bot/${StackEnv}/telegram-webhook-secret"
           GEMINI_API_KEY_PARAMETER_NAME: !Sub "/miti99bot/${StackEnv}/gemini-api-key"
           CRON_SHARED_SECRET_PARAMETER_NAME: !Sub "/miti99bot/${StackEnv}/cron-shared-secret"
-      # stats module uses non-atomic KV increment; concurrency > 1 would lose counts.
-      ReservedConcurrentExecutions: 1
       FunctionUrlConfig:
         AuthType: NONE
         InvokeMode: BUFFERED