Clean repo noise and replace dashboard DB test link with health

.gitignore

@@ -6,3 +6,10 @@ venv/
 instance/
 *.sqlite
 *.log
+
+# local backup/runtime clutter
+backups/
+run/
+backup_pre_*/
+*.bak.*
+backend/app.py.fix_indent_backup

templates/dashboard.html

@@ -37,7 +37,7 @@
         <a href="/reports/aging">Aging Report</a>
         <a href="/reports/accounting-package.zip">Monthly Accounting Package</a>
         <a href="/settings">Settings / Config</a>
-        <a href="/dbtest">DB Test</a>
+        <a href="/health">Health</a>
     </div>
 
     <form method="post" action="/reports/accounting-package/email" style="margin:0 0 16px 0;">