Refactor: Architectural cleanup of EmbeddedChatApi.ts

Description

The EmbeddedChatApi.ts file currently contains significant code duplication. Almost every API method (30+) manually retrieves the user session, constructs headers, stringifies JSON, and handles errors using redundant try/catch blocks.

Problems

1. High Redundancy: Construction of fetch options, manual JSON.stringify, and repetitive error logging account for 30% of the file size (1200+ lines). Any change to the base request logic requires modification in dozens of places.

2. Inconsistent Error Handling: Some methods log to console.error, some to console.log, and others fail silently without clear error reporting to the caller.

3. FormData Handling: Methods like sendAttachment require specific header handling (omitting Content-Type for the browser to set the boundary) which is currently handled as a one-off case.

Example

try {
  const { userId, authToken } = (await this.auth.getCurrentUser()) || {};
  const response = await fetch(`${this.host}/api/v1/SOME_ENDPOINT`, {
    headers: {
      "Content-Type": "application/json",
      "X-Auth-Token": authToken,
      "X-User-Id": userId,
    },
    method: "GET/POST",
  });
  return await response.json();
} catch (err) {
  console.error(err);
}

Start by reading EmbeddedChatApi.ts and mapping the repeated session, header, request, and error-handling paths across its API methods. Inspect how callers depend on current responses and errors; done means common request handling is introduced without breaking FormData boundary handling or existing API behavior.