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/tailwindcss/references/effects-scroll-snap.md

@@ -0,0 +1,59 @@
+---
+name: effects-scroll-snap
+description: CSS scroll snap for carousels and scroll containers
+---
+
+# Scroll Snap
+
+Utilities for scroll snap behavior in overflow containers. Use for carousels, horizontal galleries, or paged scroll.
+
+## Usage
+
+### Container
+
+```html
+<!-- Horizontal snap (carousel) -->
+<div class="snap-x snap-mandatory overflow-x-auto flex gap-4">
+  <div class="snap-center shrink-0 w-80">Slide 1</div>
+  <div class="snap-center shrink-0 w-80">Slide 2</div>
+  <div class="snap-center shrink-0 w-80">Slide 3</div>
+</div>
+
+<!-- Vertical snap -->
+<div class="snap-y snap-mandatory overflow-y-auto h-screen">
+  <div class="snap-start h-screen">Section 1</div>
+  <div class="snap-start h-screen">Section 2</div>
+</div>
+
+<!-- Both axes -->
+<div class="snap-both overflow-auto">...</div>
+```
+
+### Strictness
+
+- `snap-mandatory` - always rest on a snap point
+- `snap-proximity` - snap only when close to a point (default)
+
+### Child alignment
+
+```html
+<div class="snap-x overflow-x-auto">
+  <div class="snap-center">Center snap</div>
+  <div class="snap-start">Start snap</div>
+  <div class="snap-end">End snap</div>
+  <div class="snap-align-none">No snap</div>
+</div>
+```
+
+## Key Points
+
+- `snap-x` - horizontal; `snap-y` - vertical; `snap-both` - both; `snap-none` - disable
+- `snap-mandatory` / `snap-proximity` - strictness
+- Child: `snap-center`, `snap-start`, `snap-end`, `snap-align-none`
+- Requires overflow (e.g. `overflow-x-auto`) and scroll on container
+
+<!--
+Source references:
+- https://tailwindcss.com/docs/scroll-snap-type
+- https://tailwindcss.com/docs/scroll-snap-align
+-->