Add contribution detail page and rebrand card navigation

[JoaquinBN]

Summary

• New ContributionPreview route (/contribution/:id) with two variants: highlighted contributions show a colored hero box with the steward's article body and a gold hexagon+star icon; normal contributions show the type name and jump straight to showcase/notes.
• All contribution cards across portal highlights, profile highlights, profile recent contributions, and dashboard now navigate to /contribution/:id instead of legacy /badge/, /participant/, or /contribution-type/ routes.
• Handles grouped contribution IDs (group_*) by extracting the real contribution ID from grouped_contributions.
• Includes a full skeleton loader, sidebar with contributor info and details, "More from user" cards, and proper $derived.by reactivity for user role.

Test plan

• Click a contribution card from the portal home highlights — should open the contribution detail page
• Click a contribution card from the profile recent contributions — should open the contribution detail page (not the old contribution type view)
• Click a highlighted contribution from the profile highlights — should open with the colored hero variant
• Verify the skeleton loader displays while the page loads
• Verify non-highlighted contributions show type name → showcase → notes layout
• Verify highlighted contributions show gold hexagon+star icon, optional title, and full article body inside the colored container