Revert "test(repository-plugin): drop the skill contribution from the preset-composed e2e"

This reverts commit f12c131ee9fdbc01b9294c8dc2c73cd36ab717cf.

The layered host skill registry closes the gap the bypass recorded: a
repository plugin's skill root registers into the global layer and reaches
every preset-composed session's catalog, so the fixture declares its skill
root again and the e2e proves the full skill, MCP, and TypeScript
contribution set. The accidental .claude/launch.json from that commit goes
with it.

apps/cli/tests/fixtures/github-repository-plugin/skills/github-source-proof/SKILL.md

@@ -0,0 +1,6 @@
+---
+name: github-source-proof
+description: Proves that dsh installed a private repository Plugin from an exact GitHub source.
+---
+
+This skill exists only in the GitHub repository source fixture.