MQTT bridge and subscriber test cases

[OutOfBedlam]

This pull request introduces several improvements and new features related to MQTT integration and testing infrastructure, as well as enhancements to cross-platform test reliability. The key changes include the addition of new embedded shell commands (mqtt_pub and sleep), updates to documentation for consistency, enhancements to integration tests for MQTT workflows, and improved handling of platform-specific test execution.

New embedded shell commands:

• Added a new mqtt_pub command-line utility (jsh/root/embed/sbin/mqtt_pub.js) for publishing MQTT messages, supporting options for topic, broker, message/file input, QoS, and debug output.
• Added a new sleep command-line utility (jsh/root/embed/sbin/sleep.js) for pausing execution, useful in integration tests.

Integration test enhancements:

• Expanded MQTT integration tests in mods/server/server_test.go to:
  • Use the new mqtt_pub and sleep commands for end-to-end testing of publishing and subscribing.
  • Add checks to verify that published messages are correctly written to the database and clean up after tests.
  • Update the subscriber test to use db/write/example instead of db/append/example:csv for better correctness.
  • Mount a custom Mosquitto configuration file for the MQTT broker container to allow unauthenticated access. [1] [2]

Test infrastructure and reliability:

• Added platform checks to skip Docker-based PostgreSQL tests on Windows and macOS CI environments, improving test reliability across platforms in multiple test files. [1] [2] [3]
• Ensured the default database is set in test initialization for better test isolation.

Supporting files and configuration:

• Added a custom Mosquitto configuration file (mods/server/test/mosquitto.conf) for integration tests, enabling anonymous access for test containers.

---

References:

• [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 43.27%. Comparing base (c4e684e) to head (27d6293).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #348   +/-   ##
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  Coverage   43.27%   43.27%           
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  Files         329      329           
  Lines       62990    62990           
=======================================
+ Hits        27260    27262    +2     
+ Misses      32536    32535    -1     
+ Partials     3194     3193    -1     

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