Initial project structure for MCP interceptors (#3)

Establishes a multi-language monorepo structure for MCP interceptors
with Python and TypeScript SDKs alongside the existing Go
implementation. Implements an efficient CI/CD system that only tests
what changes.


#### 🏗️ SDK Scaffolding
- **Python SDK** (`python/sdk/`): Modern Python package using
`pyproject.toml`, aligned with official MCP Python SDK patterns
- **TypeScript SDK** (`typescript/sdk/`): ESM-based package structure,
compatible with official MCP TypeScript SDK
- **Monorepo structure**: Consistent `{language}/sdk/` pattern across
all implementations
  
 #### 🚀 CI/CD Pipeline
- **Path-based workflow triggering**: Only runs CI for languages that
actually changed
    - Change Python → only Python CI runs
    - Change multiple languages → only those CIs run
- **Status check workflow**: Single required check that dynamically
validates based on changes
- **Comment triggers**: Maintainers can run all checks with `/test all`
PR comment

python/sdk/src/mcp_ext_interceptors/__init__.py

@@ -0,0 +1,10 @@
+# Copyright 2025 The MCP Interceptors Authors. All rights reserved.
+# Use of this source code is governed by a Apache-2.0
+# license that can be found in the LICENSE file.
+
+"""
+MCP Interceptors Python SDK
+
+Implements MCP Interceptors based on SEP-1763:
+https://github.com/modelcontextprotocol/modelcontextprotocol/issues/1763
+"""

python/sdk/src/mcp_ext_interceptors/interceptor.py

@@ -0,0 +1,8 @@
+# Copyright 2025 The MCP Interceptors Authors. All rights reserved.
+# Use of this source code is governed by a Apache-2.0
+# license that can be found in the LICENSE file.
+
+"""
+Package interceptors implements MCP Interceptors based on SEP-1763:
+https://github.com/modelcontextprotocol/modelcontextprotocol/issues/1763
+"""

python/sdk/src/mcp_ext_interceptors/py.typed

@@ -0,0 +1,2 @@
+# Marker file for PEP 561
+# This file indicates that this package supports type checking