fix(#674): snapshot-test and fix shell completions for every command

[Awosdot]

Description

Brief description of what this PR does and why.

Closes #674

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 change)
• Documentation update

Changes Made

• Audited and implemented robust shell-specific snapshot tests covering completion scripts across Bash, Zsh, Fish, and PowerShell.
• Corrected parser formatting issues and broken character representations in documentation.
• Fixed PowerShell kebab-case command naming regressions and maintained strict feature isolation.

Testing

How has this been tested?

Describe the tests you ran and how to reproduce them.

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed

Test Coverage

Describe what scenarios have been tested:

• Happy path: Generated and verified shell completion scripts for Bash, Zsh, Fish, and PowerShell.
• Edge cases: Handled PowerShell kebab-case command naming and special character representations.
• Error handling: Ensured strict scoping around completion features to avoid unrelated workspace compiler or database warnings.

Code Quality Checklist

• My code follows the style guidelines of this project (cargo fmt)
• 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 (cargo clippy -- -D 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
• The CI checks pass (format, clippy, tests)

Breaking Changes

• This PR introduces breaking changes

If checked, describe the breaking changes and migration path:

Documentation

• README.md updated
• DEVELOPER_GUIDE.md updated (if applicable)
• API_REFERENCE.md updated (if applicable)
• No documentation changes needed

Screenshots (if applicable)

Add screenshots or GIFs for UI changes.

Additional Context

Add any other context about the PR here.

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Note: Make sure all tests pass locally before submitting:

cargo test
cargo fmt --all
cargo clippy -- -D warnings

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[Manuelshub]

@Awosdot Please fix all CI issues