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-object-fit-position.md

@@ -0,0 +1,64 @@
+---
+name: layout-object-fit-position
+description: Controlling how replaced elements (images, video) are resized and positioned within their container
+---
+
+# Object Fit & Object Position
+
+Utilities for controlling how replaced elements like `<img>` and `<video>` are resized and positioned within their container.
+
+## Usage
+
+### Object fit
+
+```html
+<!-- Cover container, may crop -->
+<img class="h-48 w-96 object-cover" src="photo.jpg" />
+
+<!-- Contain within, may letterbox -->
+<img class="h-48 w-96 object-contain" src="photo.jpg" />
+
+<!-- Stretch to fill -->
+<img class="h-48 w-96 object-fill" src="photo.jpg" />
+
+<!-- Scale down only if needed, else original size -->
+<img class="h-48 w-96 object-scale-down" src="photo.jpg" />
+
+<!-- Original size, ignore container -->
+<img class="h-48 w-96 object-none" src="photo.jpg" />
+```
+
+### Object position
+
+```html
+<!-- Named positions -->
+<img class="size-24 object-cover object-top-left" src="photo.jpg" />
+<img class="size-24 object-cover object-center" src="photo.jpg" />
+<img class="size-24 object-cover object-bottom-right" src="photo.jpg" />
+
+<!-- Custom value -->
+<img class="object-cover object-[25%_75%]" src="photo.jpg" />
+<img class="object-(--my-object)" src="photo.jpg" />
+```
+
+### Responsive
+
+```html
+<img class="object-contain md:object-cover object-center md:object-top" src="photo.jpg" />
+```
+
+## Key Points
+
+- `object-contain` - maintain aspect ratio, fit inside container
+- `object-cover` - maintain aspect ratio, cover container (may crop)
+- `object-fill` - stretch to fill container
+- `object-scale-down` - like `contain` but never upscale
+- `object-none` - original size, ignore container
+- Position: `object-top-left`, `object-top`, `object-top-right`, `object-left`, `object-center`, `object-right`, `object-bottom-left`, `object-bottom`, `object-bottom-right`
+- Custom: `object-[25%_75%]`, `object-(--custom-property)`
+
+<!--
+Source references:
+- https://tailwindcss.com/docs/object-fit
+- https://tailwindcss.com/docs/object-position
+-->