feat: add new OpenSpec skills for change management and onboarding

- Created `openspec-ff-change` skill for fast-forward artifact creation.
- Introduced `openspec-new-change` skill for structured change creation.
- Developed `openspec-onboard` skill for guided onboarding through OpenSpec workflow.
- Added `openspec-sync-specs` skill for syncing delta specs to main specs.
- Implemented `openspec-verify-change` skill for verifying implementation against change artifacts.
- Updated `.gitignore` to exclude OpenSpec generated files.
- Added `skills-lock.json` to manage skill dependencies.

.agents/skills/vercel-react-best-practices/rules/async-api-routes.md

@@ -0,0 +1,38 @@
+---
+title: Prevent Waterfall Chains in API Routes
+impact: CRITICAL
+impactDescription: 2-10× improvement
+tags: api-routes, server-actions, waterfalls, parallelization
+---
+
+## Prevent Waterfall Chains in API Routes
+
+In API routes and Server Actions, start independent operations immediately, even if you don't await them yet.
+
+**Incorrect (config waits for auth, data waits for both):**
+
+```typescript
+export async function GET(request: Request) {
+  const session = await auth()
+  const config = await fetchConfig()
+  const data = await fetchData(session.user.id)
+  return Response.json({ data, config })
+}
+```
+
+**Correct (auth and config start immediately):**
+
+```typescript
+export async function GET(request: Request) {
+  const sessionPromise = auth()
+  const configPromise = fetchConfig()
+  const session = await sessionPromise
+  const [config, data] = await Promise.all([
+    configPromise,
+    fetchData(session.user.id)
+  ])
+  return Response.json({ data, config })
+}
+```
+
+For operations with more complex dependency chains, use `better-all` to automatically maximize parallelism (see Dependency-Based Parallelization).