Adjust devcontainer extensions

.devcontainer/devcontainer.json

···
     "vscode": {
       "extensions": [
         "ms-vsliveshare.vsliveshare",
-        "rust-lang.rust-analyzer",
         "dbaeumer.vscode-eslint"
       ]
     }

AGENTS.md

···
 # Agent Notes
 
 - Relocated the project Dockerfile into `.devcontainer/Dockerfile` so GitHub Codespaces can pick it up automatically.
-- Added `.devcontainer/devcontainer.json` pointing to the Dockerfile, sets remote user `app`, and recommends VS Code extensions.
+- Added `.devcontainer/devcontainer.json` pointing to the Dockerfile, sets remote user `app`, and recommends necessary VS Code extensions.
+- Dropped the Rust Analyzer recommendation per project requirements; keep the list lean to essentials.
 - Remember to mirror any environment dependency updates in both the Dockerfile and devcontainer definition.