Reorganize: Move all skills to skills/ folder

- Created skills/ directory
- Moved 272 skills to skills/ subfolder
- Kept agents/ at root level
- Kept installation scripts and docs at root level

Repository structure:
- skills/           - All 272 skills from skills.sh
- agents/           - Agent definitions
- *.sh, *.ps1       - Installation scripts
- README.md, etc.   - Documentation

Co-Authored-By: Claude <noreply@anthropic.com>

skills/plugins/marketplaces/claude-plugins-official/external_plugins/slack/.claude-plugin/plugin.json

@@ -0,0 +1,7 @@
+{
+  "name": "slack",
+  "description": "Slack workspace integration. Search messages, access channels, read threads, and stay connected with your team's communications while coding. Find relevant discussions and context quickly.",
+  "author": {
+    "name": "Slack"
+  }
+}

skills/plugins/marketplaces/claude-plugins-official/external_plugins/slack/.mcp.json

@@ -0,0 +1,6 @@
+{
+  "slack": {
+    "type": "sse",
+    "url": "https://mcp.slack.com/sse"
+  }
+}