docs(skills): Replace ng-deep with tokens in generate-from-image-design skill - 21.2.x

[georgianastasov]

Description

Addresses feedback from @simeonoff on the igniteui-angular-generate-from-image-design skill.

Resolved:

SKILL.md Step 5c — Replaced "Apply the generated theme blocks inside ::ng-deep scoped to the component selector" with guidance to use @include tokens();, which works without ::ng-deep even with emulated ViewEncapsulation.

gotchas.md: Dark theme overrides for IgxGridComponent". Removed the ::ng-deep block targeting internal grid classes (.igx-grid__thead, .igx-grid__tr, etc.) and replaced it with the tokens mixin approach via create_component_theme.

Motivation / Context

These address the two related comments:

"Component theme mixins should NOT be used. When requesting a component theme from the MCP server the server returns a complete theme with @include tokens(); This should be sufficient even in Emulated view encapsulation scenarios." - #17181 (comment)

"Also the ::ng-deep should not be needed when using the tokens mixin. Not to mention that component-specific mixins have been deprecated for a long time now." - #17181 (comment)

Type of Change (check all that apply):

• Bug fix
• New functionality
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (no functional changes)
• Documentation
• Demos
• CI/CD
• Tests
• Changelog
• Skills/Agents

Component(s) / Area(s) Affected:

Skills

How Has This Been Tested?

• Unit tests
• Manual testing
• Automated e2e tests

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them
• Accessibility (ARIA, keyboard navigation, focus management) has been verified