CommandBoard web server throws on malformed path encoding

[phucnguyen1707]

The CommandBoard web server decodes static paths with decodeURIComponent(pathname). A malformed percent-encoded path can throw URIError before the server sends a client response.

Repro path:

1. Build/start the CommandBoard web server.
2. Request a malformed encoded URL such as /%E0%A4%A.
3. The path decoding throws instead of returning a clean client error.

Expected: malformed path encoding should return a 400 response.

Actual: the server can throw while resolving the static path.

A focused fix and regression test are coming in a PR.