fix(syslog): validate listener port range on save

[duguwanglong]

fix(syslog): validate listener port range on save

Follow-up to PR #267: the syslog config form already validated host but
accepted any integer for port, allowing values such as 0, 22, or 99999
to be saved and only blow up at bind time with a confusing OS error
(e.g. "[Errno 49] can't assign requested address").

- Backend SyslogConfigRequest.port now enforces ge=1, le=65535 via
  Pydantic so out-of-range ports are rejected with HTTP 422 before the
  config is persisted or the listener is restarted.
- IntegrationTab.tsx adds an inline validator that strictly matches a
  numeric string (rejecting "5140abc", "3.14", "-1", etc.) and the
  1..65535 range; the input shows a red border with a localized hint
  and the save button is disabled while the value is invalid.
- extractErrorMessage now flattens Pydantic 422 detail arrays
  ([{loc, msg, type}, ...]) into a readable "; "-joined string so
  scripted callers (or any caller that bypasses the UI validator)
  see the actual validation message instead of "[object Object]".
- Adds zh-CN/en-US copy for detail.run.syslogPortError.