docs: add badges and remove nightly from CI test matrix

Add comprehensive badges to README.md:
- CI status badge (GitHub Actions workflow)
- Code coverage badge (Codecov)
- MSRV badge (Minimum Supported Rust Version 1.88)
- License badge (MIT OR Apache-2.0)
- Rust version badge (stable)

Remove nightly from CI test matrix:
- Test only on stable (all platforms) and beta (Linux only)
- Nightly toolchain still used for rustfmt formatting checks
- Remove continue-on-error directive (no longer needed)

All 352 tests passing on stable Rust.

Author: bug-ops

.github/workflows/ci.yml

@@ -101,10 +101,6 @@ jobs:
           # Test on beta channel on Linux only
           - os: ubuntu-latest
             rust: beta
-          # Test on nightly (allow to fail)
-          - os: ubuntu-latest
-            rust: nightly
-    continue-on-error: ${{ matrix.rust == 'nightly' }}
 
     steps:
       - uses: actions/checkout@v5

README.md

@@ -2,6 +2,12 @@
 
 **Secure WebAssembly-based code execution for Model Context Protocol (MCP) with 90-98% token savings.**
 
+[![CI](https://github.com/bug-ops/mcp-execution/actions/workflows/ci.yml/badge.svg)](https://github.com/bug-ops/mcp-execution/actions/workflows/ci.yml)
+[![codecov](https://codecov.io/gh/bug-ops/mcp-execution/branch/master/graph/badge.svg)](https://codecov.io/gh/bug-ops/mcp-execution)
+[![MSRV](https://img.shields.io/badge/MSRV-1.88-blue.svg)](https://blog.rust-lang.org/2025/01/09/Rust-1.88.0.html)
+[![License](https://img.shields.io/badge/license-MIT%20OR%20Apache--2.0-blue.svg)](LICENSE-MIT)
+[![Rust](https://img.shields.io/badge/rust-stable-orange.svg)](https://www.rust-lang.org)
+
 ## Overview
 
 MCP Code Execution implements the Code Execution pattern for MCP, enabling AI agents to discover and execute MCP tools through progressive loading rather than sending full tool definitions in every prompt. This achieves dramatic token savings while maintaining full compatibility with existing MCP servers.