Add Composio SDK skill with rules and agent config

Adds composio-sdk/ with SKILL.md, AGENTS.md, and 18 rule files
covering Tool Router, direct execution, triggers, and auth patterns.

Source: composiohq/skills

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

composio-sdk/rules/tr-session-basic.md

@@ -0,0 +1,74 @@
+---
+title: Create Basic Tool Router Sessions
+impact: HIGH
+description: Essential pattern for initializing Tool Router sessions with proper user isolation
+tags: [tool-router, session, initialization, agents]
+---
+
+# Create Basic Tool Router Sessions
+
+Always create isolated Tool Router sessions per user to ensure proper data isolation and scoped tool access.
+
+## ❌ Incorrect
+
+```typescript
+// DON'T: Using shared session for multiple users
+const sharedSession = await composio.create('default', {
+  toolkits: ['gmail']
+});
+// All users share the same session - security risk!
+```
+
+```python
+# DON'T: Using shared session for multiple users
+shared_session = composio.tool_router.create(
+    user_id="default",
+    toolkits=["gmail"]
+)
+# All users share the same session - security risk!
+```
+
+## ✅ Correct
+
+```typescript
+// DO: Create per-user sessions for isolation
+import { Composio } from '@composio/core';
+
+const composio = new Composio();
+
+// Each user gets their own isolated session
+const session = await composio.create('user_123', {
+  toolkits: ['gmail', 'slack']
+});
+
+console.log('Session ID:', session.sessionId);
+console.log('MCP URL:', session.mcp.url);
+```
+
+```python
+# DO: Create per-user sessions for isolation
+from composio import Composio
+
+composio = Composio()
+
+# Each user gets their own isolated session
+session = composio.tool_router.create(
+    user_id="user_123",
+    toolkits=["gmail", "slack"]
+)
+
+print(f"Session ID: {session.session_id}")
+print(f"MCP URL: {session.mcp.url}")
+```
+
+## Key Points
+
+- **User Isolation**: Each user must have their own session
+- **Toolkit Scoping**: Specify which toolkits the session can access
+- **Session ID**: Store the session ID to retrieve it later
+- **MCP URL**: Use this URL with any MCP-compatible AI framework
+
+## Reference
+
+- [Tool Router API Docs](https://docs.composio.dev/sdk/typescript/api/tool-router)
+- [Creating Sessions](https://docs.composio.dev/sdk/typescript/api/tool-router#creating-sessions)