ci: migrate issue #523 to internal linting tool

[josecelano]

Summary

• implement issue Install MegaLinter #523 using internal Torrust linting tool instead of MegaLinter
• add/adapt linter config files for markdown, yaml, and toml
• fix lint violations by category (clippy, cspell, markdown, yaml, toml) with separate commits
• update .github/workflows/testing.yaml static-analysis job to run linter all

Why

Use the organization internal linting workflow for consistent lint behavior across Torrust repositories.

Validation

• local linter all passes

Related

• Closes Install MegaLinter #523

[josecelano]

ACK 1d3ba50

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.44%. Comparing base (1ef5b41) to head (1d3ba50).
⚠️ Report is 9 commits behind head on develop.

Files with missing lines	Patch %	Lines
...ackages/axum-rest-tracker-api-server/src/server.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1680   +/-   ##
========================================
  Coverage    86.44%   86.44%           
========================================
  Files          288      288           
  Lines        22672    22672           
  Branches     22672    22672           
========================================
  Hits         19599    19599           
  Misses        2840     2840           
  Partials       233      233           

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[josecelano]

ACK 1d3ba50