docs(commands): Expand and update command reference with new features and flags

[thomas-vilte]

Description

This PR provides a comprehensive update to the COMMANDS.md and README.md documentation, including their Spanish translations. I have expanded the command reference to accurately reflect the latest features and functionalities introduced in the matecommit CLI. This includes detailed explanations for the newly added issue and release subcommands, along with their various flags and workflows. The suggest and summarize-pr commands have also received updates to document new flags like --interactive and --dry-run, and expanded descriptions of their operational flow. Furthermore, I have documented new system commands such as cache, completion, and update, and clarified the config and doctor commands, including the new .json configuration file structure and enhanced troubleshooting tips. The README.md has been updated to reflect the new config init command and highlight the cost tracking feature.

Fixes # (issue)

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

I have manually reviewed all modified markdown files (COMMANDS.md, README.md, docs/es/COMMANDS.md, docs/es/README.md) to ensure the accuracy, completeness, and clarity of the updated command descriptions, flags, and usage examples. I verified that all new commands and flags are correctly represented and that the Spanish translations are consistent with the English versions.

• Unit tests
• Integration tests
• Manual test: (described above)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

🧪 Test Plan & Evidence

Suggested Manual Verification

• No Regressions: Verify that related features still work as expected