feat(skills): surface source repository and tighten registry metadata

[samuv]

Following #2045, this PR brings the skills registry closer to parity with MCP servers: the upstream repo is one click away from every view, the SKILL.md preview drops the metadata we already render as badges, and the detail page stops resizing between skills.

The registry response distinguishes between namespace (packager, e.g. io.github.stacklok) and repository.url (upstream source, e.g. github.com/trailofbits/skills). Today only namespace is visible — it's not obvious the skill was authored elsewhere and packaged downstream. MCP servers already solve this via repository_url; this PR lines the two up.

Changes

• Card / table / detail — link skill.repository.url with the same GitHub-icon pattern used for MCP servers: ghost icon on the card footer, an icon-only trailing column on the registry table, and an outline GitHub button next to Install on the detail page. All three render nothing when repository is absent, and their click handlers stop propagation so card/row navigation isn't triggered.
• Table column rename — Author → Registry. The column holds the reverse-DNS namespace (the packager/registry), not the author.
• SKILL.md preview — enable stripFrontmatter on the registry detail. SkillMarkdown already supported it; only the build detail was passing it. Preview now starts at the first heading instead of the YAML block duplicating name / description / license / version.
• Detail layout — the right panel was flex-1 without min-w-0, so wide SKILL.md content (code blocks, tables) pushed the column past its 7/12 allotment and varied between skills. Adding min-w-0 lets the flex child shrink; overflow now scrolls inside the card. Applies to both registry and build detail pages (shared layout).

How to validate

1. Registry tab — card footer has a GitHub icon; opens the upstream repo in a new tab, card stays in place.
2. Table view — Registry header (previously Author); GitHub icon sits between About and Install.
3. Skill detail (e.g. io.github.stacklok/agentic-actions-auditor) — GitHub button next to Install; SKILL.md starts at the first heading; card width is identical across skills.

[Copilot]

Pull request overview

This PR improves the skills registry UX to better match the MCP servers experience by exposing upstream repository metadata, reducing duplicated SKILL.md metadata rendering, and stabilizing the skill detail layout width.

Changes:

• Add upstream repository (GitHub) links to registry skill card, table, and detail views when skill.repository.url is present.
• Rename the table column label from Author to Registry to reflect the namespace/packager value.
• Strip YAML frontmatter from SKILL.md previews and prevent the detail right panel from expanding layout width (min-w-0).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
renderer/src/features/skills/components/table-registry-skills.tsx	Adds repository icon column/link and renames “Author” → “Registry”.
renderer/src/features/skills/components/skill-detail-page.tsx	Adds GitHub button/link and enables stripFrontmatter for SKILL.md rendering.
renderer/src/features/skills/components/skill-detail-layout.tsx	Adds min-w-0 to stabilize right panel sizing/overflow behavior.
renderer/src/features/skills/components/card-registry-skill.tsx	Adds GitHub icon link in the card footer next to Install.
renderer/src/features/skills/components/tests/table-registry-skills.test.tsx	Updates column header assertion and adds coverage for repository link behavior.
renderer/src/features/skills/components/tests/card-registry-skill.test.tsx	Adds coverage for repository link presence and click not triggering navigation.

[peppescg]

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