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/layout-overflow.md

@@ -0,0 +1,57 @@
+---
+name: layout-overflow
+description: Controlling how elements handle content that overflows their container
+---
+
+# Overflow
+
+Utilities for controlling how an element handles content that is too large for the container.
+
+## Usage
+
+### Basic overflow
+
+Use `overflow-auto`, `overflow-hidden`, `overflow-visible`, `overflow-scroll`:
+
+```html
+<div class="overflow-auto">Scrolls if needed</div>
+<div class="overflow-hidden">Clips overflow</div>
+<div class="overflow-visible">Shows overflow</div>
+<div class="overflow-scroll">Always shows scrollbars</div>
+```
+
+### Axis-specific overflow
+
+Use `overflow-x-*` or `overflow-y-*` for horizontal/vertical control:
+
+```html
+<div class="overflow-x-auto overflow-y-hidden">
+  Horizontal scroll, vertical clip
+</div>
+<div class="overflow-x-scroll overflow-y-auto">
+  Horizontal always scrolls, vertical scrolls if needed
+</div>
+```
+
+### Overflow clip
+
+Use `overflow-clip` for clip behavior (similar to hidden but different scroll behavior):
+
+```html
+<div class="overflow-clip">Clips without creating scroll container</div>
+```
+
+## Key Points
+
+- `overflow-auto` - shows scrollbars only when needed
+- `overflow-hidden` - clips content that overflows
+- `overflow-visible` - allows content to overflow (default for most elements)
+- `overflow-scroll` - always shows scrollbars
+- `overflow-clip` - clips without creating scroll container
+- Use `overflow-x-*` and `overflow-y-*` for axis-specific control
+- Common pattern: `overflow-hidden` for images, `overflow-auto` for scrollable content
+
+<!--
+Source references:
+- https://tailwindcss.com/docs/overflow
+-->