fix: keep credentials out of HTTP errors

[CodingInAVan]

This PR hardens the agent’s HTTP upload path so authentication credentials cannot appear in exception messages or logs.

What changed

• Trim transport whitespace from API tokens before creating the authorization header.
• Handle trailing CR/LF characters commonly introduced by environment variables or copied secrets.
• Replace raw exception-message logging with a sanitized exception-type description.
• Preserve useful failure classification without exposing request headers, tokens, or other sensitive values.
• Add regression tests covering token normalization and secret non-disclosure.

Why

HTTP client exceptions can include request details depending on the failure path and runtime implementation. Logging the raw exception message creates a risk that an API token may be written to local logs or CI output.

The agent now reports the failure category while keeping credential material out of the diagnostic message.

Validation

• Full Gradle test suite passed.
• All 17 HttpPublisherTest cases passed.
• Shadow JAR build completed successfully.
• Added tests for:
  • CR/LF token trimming.
  • Secrets embedded in exception messages.
  • Failure logging without credential disclosure.