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.

skills-lock.json

@@ -0,0 +1,35 @@
+{
+  "version": 1,
+  "skills": {
+    "astro": {
+      "source": "astrolicious/agent-skills",
+      "sourceType": "github",
+      "computedHash": "597a4587f30f1152d3ab2923e84db842a18604e09e16885ffa067730fb435d9d"
+    },
+    "framer-motion": {
+      "source": "mindrally/skills",
+      "sourceType": "github",
+      "computedHash": "39a33b58952788812d305f7b676b86ee800d3d5be9752e10392435d7fae73d8a"
+    },
+    "shadcn": {
+      "source": "shadcn/ui",
+      "sourceType": "github",
+      "computedHash": "91c02eb706f046fb9d6a061efbb96496e4be751b5b14c283cf82baaa50f3a985"
+    },
+    "tailwindcss": {
+      "source": "hairyf/skills",
+      "sourceType": "github",
+      "computedHash": "676d95536c3c4a64215535ff09128d6e8d5163eb3fc204ed2cfde61e87b5d892"
+    },
+    "tailwindcss-advanced-layouts": {
+      "source": "josiahsiegel/claude-plugin-marketplace",
+      "sourceType": "github",
+      "computedHash": "fa08c5757b8f24df2d412543d370bc25d8c14eadeb27be4112b2354323f5889f"
+    },
+    "vercel-react-best-practices": {
+      "source": "vercel-labs/agent-skills",
+      "sourceType": "github",
+      "computedHash": "afeca00ac2f492d88fdd010e73d91719a5b57c564bb4a73325b0bd77e11323ab"
+    }
+  }
+}