build(deps): Upgrade MCP SDK to 1.27.1

Update @modelcontextprotocol/sdk from ^1.25.1 to ^1.27.1 so local
and harness testing run on the latest SDK behavior.

Add /repros to .gitignore to keep lifecycle repro artifacts out of
source control during repeated leak investigations.

Refs #273
Co-Authored-By: Codex <noreply@openai.com>

Author: cameroncooke

.gitignore

@@ -111,3 +111,4 @@ bundled/
 DerivedData
 .derivedData
 /.pr-learning
+/repros

package-lock.json

@@ -74,7 +74,7 @@
   },
   "dependencies": {
     "@clack/prompts": "^1.0.1",
-    "@modelcontextprotocol/sdk": "^1.25.1",
+    "@modelcontextprotocol/sdk": "^1.27.1",
     "@sentry/cli": "^3.1.0",
     "@sentry/node": "^10.43.0",
     "bplist-parser": "^0.3.2",