fix: allow Auth0 lowercase template variables to pass keyword placeholder validation

[harshithRai]

Auth0 SMS connections support native template variables like @@password@@ that were being incorrectly flagged as unresolved keyword placeholders, causing imports to fail.

🔧 Changes

• Tightened the unresolved placeholder regex to only match uppercase patterns ([A-Z0-9_]), aligning with the established deploy-cli keyword convention (@@MY_KEY@@, ##MY_SECRET##). Lowercase Auth0-native template variables are no longer flagged as unresolved.

📚 References

Auth0 SMS template variables documentation

🔬 Testing

Unit tests:

• Updated an existing test in test/tools/utils.test.js to include a lowercase @@...@@ value, confirming it no longer throws

Manual end-to-end:

• Created an SMS passwordless connection in a test tenant with template: @@password@@
• Exported the tenant with a0deploy export --format yaml
• Before applying fix: import failed with Unresolved placeholder(s) found in connections: "options.template": @@password@@
• After applying fix: import completed successfully - SMS connection updated without error
• Confirmed uppercase unresolved placeholders (e.g. ##CONNECTIONS_OAUTH2_SECRET##) still correctly throw an error

📝 Checklist

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.19%. Comparing base (fedb588) to head (1da5fcc).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1408   +/-   ##
=======================================
  Coverage   80.19%   80.19%           
=======================================
  Files         153      153           
  Lines        7119     7119           
  Branches     1573     1573           
=======================================
  Hits         5709     5709           
  Misses        760      760           
  Partials      650      650           

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