feat: Replace python tests with native E2E test suite and fix capabilities schema

- Added native E2E test suite in stub to validate server<->stub<->nvim IPC
- Added win-nvim integration tests
- Fixed empty capabilities schema in initialize response in server and win-nvim
- Refactored server to accept dynamic MCP_PORT for test isolation
- Made server exit gracefully on port 3000 collision

win-nvim/src/main.rs

@@ -56,7 +56,10 @@ async fn main() {
                         jsonrpc: "2.0".to_string(),
                         id,
                         result: Some(json!({
-                            "capabilities": {},
+                            "protocolVersion": "2024-11-05",
+                            "capabilities": {
+                                "tools": {}
+                            },
                             "serverInfo": {
                                 "name": "mcp-memory-win-nvim",
                                 "version": "0.1.0"
@@ -329,7 +332,27 @@ async fn main() {
 }
 
 async fn get_socket_path() -> Result<String, String> {
-    // 1. Try auto-discovery in \\.\pipe\
+    // 1. Primary: Use the active_nvim.txt which is updated by Neovim's BufEnter telemetry
+    let profile = std::env::var("USERPROFILE").unwrap_or_else(|_| "C:\\Users\\reazul.ashraf".into());
+    let path = format!("{}\\.gemini\\active_nvim.txt", profile);
+    
+    if let Ok(content) = std::fs::read_to_string(&path) {
+        let p = content.trim().to_string();
+        if !p.is_empty() {
+            // It might be a full pipe path or just the name. If it's just the name, prepend \\.\pipe\
+            if p.starts_with(r"\\.\pipe\") {
+                return Ok(p);
+            } else if p.starts_with("nvim.") {
+                return Ok(format!(r"\\.\pipe\{}", p));
+            } else {
+                // Some other servername format? Try it as is.
+                return Ok(p);
+            }
+        }
+    }
+
+    // 2. Fallback to auto-discovery in \\.\pipe\ (only if single instance is running)
+    tracing::warn!("active_nvim.txt missing or invalid, falling back to pipe discovery");
     if let Ok(dir) = std::fs::read_dir(r"\\.\pipe\") {
         for entry in dir.flatten() {
             let name = entry.file_name();
@@ -339,17 +362,6 @@ async fn get_socket_path() -> Result<String, String> {
             }
         }
     }
-
-    // 2. Fallback to active_nvim.txt
-    let profile = std::env::var("USERPROFILE").unwrap_or_else(|_| "C:\\Users\\reazul.ashraf".into());
-    let path = format!("{}\\.gemini\\active_nvim.txt", profile);
-    
-    if let Ok(content) = std::fs::read_to_string(&path) {
-        let p = content.trim().to_string();
-        if !p.is_empty() {
-            return Ok(p);
-        }
-    }
     
     Err("Could not find active Windows Neovim named pipe".to_string())
 }