feat(pair-corpus-honesty): add vibe-py, vfc-js and agent-vfc slices with mechanism vocabulary

Tasks 1.1, 5.1, 5.2, 5.4 and the data half of 5.3.

- mechanisms.toml: closed vocabulary v1 (20 ids) every expected row cites.
- vibe-py: 35 Real-Vuln-Benchmark pairs (Apache-2.0), human provenance only
  because the LLM-generated repositories carry no license (escalated).
- vfc-js: 17 Node fix-commit pairs harvested upstream (MIT/Apache-2.0),
  SecBench.js itself is not vendored (no license); sinks derived on 13/17.
- agent-vfc: 29 agent-trailer fixes as catalog-candidates.toml plus
  REVIEW.md; the loaded catalog stays empty until a human reviews them.
- datasets.toml and README document every slice and its review status.

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

benchmarks/pairs/agent-vfc/market-cap-route-4f8ae9/fixed.ts

@@ -0,0 +1,31 @@
+// Provenance: navaneethbv/market-cap  (fixed).
+// repo: navaneethbv/market-cap
+// commit: 4f8ae9be5519ced5a975f1190e3e4bc43f84e4d6
+// parent: fec6f024ce72c9c47b61cbac6ce7a35cb2280602
+// commit_url: https://github.com/navaneethbv/market-cap/commit/4f8ae9be5519ced5a975f1190e3e4bc43f84e4d6
+// cve: 
+// license: MIT
+// function: GET
+// relpath: app/auth/confirm/route.ts
+// provenance: agent
+// mechanism: source_reaches_sink
+
+export async function GET(request: NextRequest) {
+  const { searchParams } = new URL(request.url);
+  const token_hash = searchParams.get("token_hash");
+  const type = searchParams.get("type") as EmailOtpType | null;
+  const nextParam = searchParams.get("next") ?? "/";
+  // Only allow same-origin relative paths to prevent open redirects
+  const next =
+    nextParam.startsWith("/") && !nextParam.startsWith("//") ? nextParam : "/";
+
+  if (token_hash && type) {
+    const supabase = await createClient();
+    const { error } = await supabase.auth.verifyOtp({ type, token_hash });
+    if (!error) {
+      return NextResponse.redirect(new URL(next, request.url));
+    }
+  }
+
+  return NextResponse.redirect(new URL("/login?error=confirm", request.url));
+}