feat(atomic): migrate atomic-smart-snippet-source to Lit

[Copilot]

✅ Checklist

• 🧪 The component is unit tested
• 🧪 The component includes E2E tests - N/A for internal components, tested through parent components
• 🗑️ Old Cypress tests exclusive to the component are removed - None existed
• 📖 The component is documented in storybook with an .mdx file - N/A for internal components
• ♿ The component complies with the Web Content Accessibility Guidelines.
• 🌐 All strings intended for humans or assistive technology must be localized with i18n.
• 📦 The Lit component is exported in the appropriate index.ts and lazy-index.ts files - Auto-registered via @customElement
• 🎨 CSS parts are documented still accessible.
• 🦥 Slotted Content, public methods and properties are documented
• 🔄 The component outputs the same Angular output as before with Stencil
• 🏷️ The component declares the component type in the HTMLElementTagNameMap - Removed to avoid conflict with Stencil-generated types during transition

https://coveord.atlassian.net/browse/KIT-5063

Description

Migrated atomic-smart-snippet-source from Stencil to Lit. This internal component renders source URL and title links for smart snippets across search and insight interfaces.

Changes

Component Migration

• Light DOM preservation: Applied LightDomMixin to match Stencil's shadow: false
• Event handling: Custom events (selectSource, beginDelayedSelectSource, cancelPendingSelectSource) now use Lit's buildCustomEvent
• Link rendering: Migrated to use Lit-based renderLinkWithItemAnalytics functional component
• Result context: Event listener pattern for atomic/resolveResult replaces Stencil's @Listen decorator
• Directory structure: Organized into atomic-smart-snippet-source/ with Stencil version preserved as stencil-atomic-smart-snippet-source.tsx

Testing

15 unit tests covering initialization, rendering, event dispatch, result context, attribute application, and cleanup. No E2E or Storybook artifacts needed—internal component tested through parent smart-snippet components.

Technical Notes

Component serves as a child element in:

• atomic-smart-snippet / atomic-smart-snippet-suggestions (search)
• atomic-insight-smart-snippet / atomic-insight-smart-snippet-suggestions (insight)

HTMLElementTagNameMap declaration intentionally omitted to prevent type conflicts with Stencil-generated definitions during the migration period.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Migrate atomic-smart-snippet-source</issue_title>
<issue_description>

Jira Issue: KIT-5063

Type: Story
Status: New
Priority: Medium

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Comments on the Issue (you are @copilot in this section)

Custom agent used: StencilToLitMigrationV1
Specialized agent for migrating Atomic Stencil code to Lit (components, functional components, and utils)

• Fixes Migrate atomic-smart-snippet-source #6347

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