v2.0.0: error-channel APIs, correctness fixes, and server hardening

BREAKING CHANGES:
- Guard interface: Guard(ctx Ctx) error; returning error short-circuits
  (subsequent guards and the method no longer execute)
- Wired[T]() (*T, error); New() may return error; failed wiring is sticky
- BindService/BindGuard/BindRoute return error; routes accept guards
  (guards receive merged query/form params as Ctx.State)
- registration panics after Start; Ctx.Ip honors X-Forwarded-For/X-Real-IP
- internal errors sanitized to fixed client messages

FIXES:
- int64 precision loss: /cell data decoded from raw JSON bytes and
  responses serialized with json.Number (no float64 round-trip)
- enum values range-checked before uint8 conversion (256 no longer
  truncates to 0 and slips through)
- logger: files failing name parsing are no longer deleted; log channel
  never blocks request goroutines; ConfigLogger is race-free;
  logWriterWorker unlock bug fixed
- stream writer panics recovered (process no longer crashes);
  streamDone closed exactly once
- generated Go client emits definitions for pointer-to-enum/struct fields
- anonymous structs rejected at registration; isPrivate safe on empty names
- removed dead Result.Id and RequestInfo.Type

ADDITIONS:
- graceful shutdown (Shutdown), StartOn, server timeouts by default
  (Read 60s/Idle 120s/Write off), SetTimeouts/SetMaxConcurrency
- big-int-safe JSON in the generated TS client (>2^53 as BigInt)
- example/ demo services and cmd/genexample artifact generator

guard.go

@@ -1,5 +1,10 @@
 package fun
 
+// Guard 方法调用前的拦截器。
+//
+// 返回 nil 放行；返回 error 短路：后续 Guard 与业务方法不再执行，
+// error 走统一 Result 错误响应（返回 fun.Error(code, msg) 可携带错误码）。
+// 不再需要通过写响应或 panic 表达拒绝
 type Guard interface {
-	Guard(ctx Ctx)
+	Guard(ctx Ctx) error
 }