fix: percent-encode path parameters in sendRequest

[RaphaelFakhri]

Summary

ApiClient.sendRequest substituted path parameters into the URL without encoding them. A value that contains /, ?, # or % changed the request instead of identifying a resource. For example, getMessage({ id: 'a/b' }) requested /messages/a/b, and an id containing # or ? was cut off at that character.

Each value is now encoded with encodeURIComponent before it replaces its {name} token in the path template. Plain ids (letters, digits, -, _) are unchanged. Values with :, such as feed ids, go on the wire as %3A, which is how stream-py (quote(v, safe="")) and getstream-go (url.QueryEscape) already send path parameters.

Testing

__tests__/path-params.test.ts mocks fetch and checks the requested URL for plain values, reserved characters, and several path parameters in one URL. It needs no API credentials.

yarn vitest run __tests__/path-params.test.ts

Prettier and ESLint are clean on the changed files.