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

go/sdk/README.md

@@ -0,0 +1,3 @@
+# MCP Interceptors - Go Implementation
+
+This will contain the Go implementation of the MCP Interceptors based on [SEP-1763](https://github.com/modelcontextprotocol/modelcontextprotocol/issues/1763).

go/sdk/go.mod

@@ -0,0 +1,4 @@
+module github.com/modelcontextprotocol/ext-interceptors/go/sdk
+
+go 1.23.0
+

go/sdk/interceptors/interceptor.go

@@ -0,0 +1,6 @@
+// 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).
+package interceptors

go/sdk/interceptors/interceptor_test.go

@@ -0,0 +1,14 @@
+// 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
+
+import "testing"
+
+func TestPlaceholder(t *testing.T) {
+	// Placeholder test to ensure go test runs successfully
+	if false {
+		t.Error("This should not happen")
+	}
+}