fix: reconcile .claude/skills blobs with hardlinked .agents/skills

The skill SKILL.md files are hardlinked across .agents/skills/ and
.claude/skills/ (same inode, two paths), but git had committed divergent
blobs: the .agents/ copies carried an "Extended reference: AGENTS.md"
note that the .claude/ copies lacked. Because one physical file cannot
match two different blobs, the working tree was permanently dirty on the
three .claude/skills paths.

Stage the .claude copies so both paths commit identical content (with the
AGENTS.md reference note, the fuller intended version). Restores a clean
git status and keeps it clean across checkouts.

Affected skills: flux-best-practices, vercel-composition-patterns,
vercel-react-best-practices.

.claude/skills/vercel-composition-patterns/SKILL.md

@@ -19,6 +19,8 @@ boolean prop proliferation by using compound components, lifting state, and
 composing internals. These patterns make codebases easier for both humans and AI
 agents to work with as they scale.
 
+> **Extended reference:** [`AGENTS.md`](AGENTS.md) in this directory is the long-form upstream guide (vendored from Vercel). It is supplementary reference material scoped to this skill only — `SKILL.md` is the loadable entry point and the authority. It does not override or extend the repository-root `AGENTS.md` / `AGENT_GUIDE.md`.
+
 ## When to Apply
 
 Reference these guidelines when: