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

cmd/genexample/main.go

@@ -0,0 +1,34 @@
+// genexample 重新生成 example/gen 下的客户端产物（Go + TS）。
+// 在仓库根目录执行：go run ./cmd/genexample
+package main
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+
+	"github.com/cyi-cc/fun"
+	"github.com/cyi-cc/fun/example/demo"
+)
+
+func main() {
+	f := fun.New()
+	for _, svc := range []any{&demo.OrderSvc{}, &demo.ChatSvc{}} {
+		f.BindServiceForGen(svc) // 只登记元信息，不触发依赖装配
+	}
+	fun.SetOutput("./example/gen")
+	fun.GenCode(fun.GenGo{}, fun.GenTs{})
+
+	err := filepath.WalkDir("./example/gen", func(path string, d fs.DirEntry, err error) error {
+		if err == nil && !d.IsDir() {
+			rel, _ := filepath.Rel("./example/gen", path)
+			fmt.Println("生成:", filepath.ToSlash(rel))
+		}
+		return err
+	})
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "walk output:", err)
+		os.Exit(1)
+	}
+}