Extract checkRateLimit and observeStats into their own file (observe.go).
Fix the one-tick event-loss bug in observeStats where the retry path used
'unconditional break' instead of fallthrough, causing events collected
after a successful retry to be discarded.
Add 87 unit tests across 7 files (helpers, metadata, conn, handler,
connect, forward, bind) covering all handler modes, error paths,
observer/stats integration, and conn wrapper edge cases.
handler.go: -43 lines (unused observer import, extracted functions)
observe.go: +52 lines (checkRateLimit, observeStats with fallthrough fix)
test files: +1959 lines
ginuerzh