refactor: rebrand from cs-agent to BossChat

- Rename Go module: cs-agent → bosschat
- Rename all import paths across 200+ Go files
- Rename SDK: cs-ai-agent-sdk → bosschat-sdk
- Rename message protocol: cs-agent:* → bosschat:*
- Rename JS globals: CSAgentConfig → BossChatConfig
- Rename CSS classes: cs-agent-* → bosschat-*
- Update Makefile APP_NAME and ARCHIVE_NAME
- Update logo assets
- Fix display name: BoosChat → BossChat

internal/ai/application/runtime/prepare_service.go

@@ -1,6 +1,6 @@
 package runtime
 
-import "cs-agent/internal/ai/runtime/registry"
+import "bosschat/internal/ai/runtime/registry"
 
 func newPrepareService(catalog *toolCatalog) *prepareService {
 	return &prepareService{catalog: catalog}

internal/ai/application/runtime/service.go

@@ -3,8 +3,8 @@ package runtime
 import (
 	"context"
 
-	"cs-agent/internal/ai/runtime/executor"
-	"cs-agent/internal/pkg/utils"
+	"bosschat/internal/ai/runtime/executor"
+	"bosschat/internal/pkg/utils"
 )
 
 type Service struct {

internal/ai/application/runtime/summary_builder.go

@@ -1,7 +1,7 @@
 package runtime
 
 import (
-	"cs-agent/internal/ai/runtime/executor"
+	"bosschat/internal/ai/runtime/executor"
 	"strings"
 )
 

internal/ai/application/runtime/tool_catalog.go

@@ -4,10 +4,10 @@ import (
 	"encoding/json"
 	"strings"
 
-	"cs-agent/internal/ai/runtime/registry"
-	"cs-agent/internal/ai/runtime/tools"
-	"cs-agent/internal/models"
-	"cs-agent/internal/pkg/toolx"
+	"bosschat/internal/ai/runtime/registry"
+	"bosschat/internal/ai/runtime/tools"
+	"bosschat/internal/models"
+	"bosschat/internal/pkg/toolx"
 )
 
 type toolCatalog struct {

internal/ai/application/runtime/tool_catalog_test.go

@@ -3,8 +3,8 @@ package runtime
 import (
 	"testing"
 
-	"cs-agent/internal/models"
-	"cs-agent/internal/pkg/toolx"
+	"bosschat/internal/models"
+	"bosschat/internal/pkg/toolx"
 )
 
 func TestNormalizeAllowedToolCodes(t *testing.T) {

internal/ai/application/runtime/types.go

@@ -1,8 +1,8 @@
 package runtime
 
 import (
-	"cs-agent/internal/ai/runtime/registry"
-	"cs-agent/internal/models"
+	"bosschat/internal/ai/runtime/registry"
+	"bosschat/internal/models"
 )
 
 type Request struct {