refactor(schema): drop cli shim packages, add testseam swap, consolidate ForTest helpers

- import 统一：删除 cli/contractfinal 与 cli/runtimeannotate 垫片包，
  26 个消费文件一律直引 corecmd/*；cli 根仅保留 runtime_schema_seam.go
  包内别名，依赖图保持单向无环
- 新增 internal/testseam.Swap[T]：包级 var 注入缝置换由 t.Cleanup
  结构性恢复；迁移 pipeline*/stdinIsTerminalFn/loadReviewedCommandRegistry/
  schemaCommandCatalogError/schemaParameterBindingData/finalSchemaAgentMetadata
  六组核心缝（26+ 处）
- ForTest 辅助归拢到 per-package fortest.go（corecmd/contract、
  corecmd/contractfinal、shortcut、cli），生产文件只留真逻辑
- 文档同步：runtime_schema_seam.go / runtimeannotate/doc.go 注释、
  CHANGELOG、RFC §278-279、AGENTS.md

internal/generator/agentmetadata/metadata_helpers_coverage_test.go

@@ -12,8 +12,9 @@ import (
 	"testing"
 
 	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/cli"
-	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/cli/contractfinal"
 	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/corecmd/contract"
+	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/corecmd/contractfinal"
+	"github.com/DingTalk-Real-AI/dingtalk-workspace-cli/internal/testseam"
 	"github.com/spf13/cobra"
 )
 
@@ -337,60 +338,52 @@ func TestCrossPlatformCoverageMetadataSourceAndPathEdges(t *testing.T) {
 	if _, _, _, err := GenerateFromCommandRoot(".", nil, Options{}); err == nil || !strings.Contains(err.Error(), "schema source root is nil") {
 		t.Fatalf("GenerateFromCommandRoot nil root = %v", err)
 	}
-	prevBuild := pipelineBuildEffectiveRegistry
-	prevBind := pipelineBindEffectiveRegistry
-	prevGenerate := pipelineGenerateMetadata
-	t.Cleanup(func() {
-		pipelineBuildEffectiveRegistry = prevBuild
-		pipelineBindEffectiveRegistry = prevBind
-		pipelineGenerateMetadata = prevGenerate
-	})
-	pipelineBuildEffectiveRegistry = func(*cobra.Command) (cli.EffectiveCommandRegistry, error) {
+	testseam.Swap(t, &pipelineBuildEffectiveRegistry, func(*cobra.Command) (cli.EffectiveCommandRegistry, error) {
 		return cli.EffectiveCommandRegistry{}, nil
-	}
-	pipelineBindEffectiveRegistry = func(*cobra.Command, cli.EffectiveCommandRegistry) (cli.BoundCommandRegistry, error) {
+	})
+	testseam.Swap(t, &pipelineBindEffectiveRegistry, func(*cobra.Command, cli.EffectiveCommandRegistry) (cli.BoundCommandRegistry, error) {
 		return cli.BoundCommandRegistry{}, nil
-	}
-	pipelineGenerateMetadata = func(Options) (File, Stats, error) {
+	})
+	testseam.Swap(t, &pipelineGenerateMetadata, func(Options) (File, Stats, error) {
 		return File{}, Stats{}, nil
-	}
+	})
 	if _, _, _, err := GenerateFromCommandRoot("  ", &cobra.Command{Use: "dws"}, Options{}); err != nil {
 		t.Fatalf("GenerateFromCommandRoot empty rootPath defaults: %v", err)
 	}
-	pipelineBuildEffectiveRegistry = func(*cobra.Command) (cli.EffectiveCommandRegistry, error) {
+	testseam.Swap(t, &pipelineBuildEffectiveRegistry, func(*cobra.Command) (cli.EffectiveCommandRegistry, error) {
 		return cli.EffectiveCommandRegistry{}, errors.New("build boom")
-	}
+	})
 	if _, _, _, err := GenerateFromCommandRoot(".", &cobra.Command{Use: "dws"}, Options{}); err == nil || !strings.Contains(err.Error(), "build effective") {
 		t.Fatalf("build error = %v", err)
 	}
-	pipelineBuildEffectiveRegistry = func(*cobra.Command) (cli.EffectiveCommandRegistry, error) {
+	testseam.Swap(t, &pipelineBuildEffectiveRegistry, func(*cobra.Command) (cli.EffectiveCommandRegistry, error) {
 		return cli.EffectiveCommandRegistry{}, nil
-	}
-	pipelineBindEffectiveRegistry = func(*cobra.Command, cli.EffectiveCommandRegistry) (cli.BoundCommandRegistry, error) {
+	})
+	testseam.Swap(t, &pipelineBindEffectiveRegistry, func(*cobra.Command, cli.EffectiveCommandRegistry) (cli.BoundCommandRegistry, error) {
 		return cli.BoundCommandRegistry{}, errors.New("bind boom")
-	}
+	})
 	if _, _, _, err := GenerateFromCommandRoot(".", &cobra.Command{Use: "dws"}, Options{}); err == nil || !strings.Contains(err.Error(), "bind effective") {
 		t.Fatalf("bind error = %v", err)
 	}
-	pipelineBindEffectiveRegistry = func(*cobra.Command, cli.EffectiveCommandRegistry) (cli.BoundCommandRegistry, error) {
+	testseam.Swap(t, &pipelineBindEffectiveRegistry, func(*cobra.Command, cli.EffectiveCommandRegistry) (cli.BoundCommandRegistry, error) {
 		return cli.BoundCommandRegistry{}, nil
-	}
-	pipelineGenerateMetadata = func(Options) (File, Stats, error) {
+	})
+	testseam.Swap(t, &pipelineGenerateMetadata, func(Options) (File, Stats, error) {
 		return File{}, Stats{}, errors.New("generate boom")
-	}
+	})
 	if _, _, _, err := GenerateFromCommandRoot(".", &cobra.Command{Use: "dws"}, Options{}); err == nil || !strings.Contains(err.Error(), "generate in-memory") {
 		t.Fatalf("generate error = %v", err)
 	}
-	pipelineBuildEffectiveRegistry = func(*cobra.Command) (cli.EffectiveCommandRegistry, error) {
+	testseam.Swap(t, &pipelineBuildEffectiveRegistry, func(*cobra.Command) (cli.EffectiveCommandRegistry, error) {
 		return cli.EffectiveCommandRegistry{Commands: []cli.CommandSpec{{
 			CanonicalPath:  "coverage.missing",
 			PrimaryCLIPath: "coverage missing",
 			Visibility:     cli.SchemaVisibilityPublic,
 		}}}, nil
-	}
-	pipelineBindEffectiveRegistry = func(*cobra.Command, cli.EffectiveCommandRegistry) (cli.BoundCommandRegistry, error) {
+	})
+	testseam.Swap(t, &pipelineBindEffectiveRegistry, func(*cobra.Command, cli.EffectiveCommandRegistry) (cli.BoundCommandRegistry, error) {
 		return cli.BoundCommandRegistry{}, nil
-	}
+	})
 	if _, _, _, err := GenerateFromCommandRoot(".", &cobra.Command{Use: "dws"}, Options{}); err == nil || !strings.Contains(err.Error(), "selection coverage incomplete") {
 		t.Fatalf("selection coverage error = %v", err)
 	}