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/pkg/toolx/builtin_tools.go

@@ -3,7 +3,7 @@ package toolx
 import (
 	"strings"
 
-	"cs-agent/internal/pkg/enums"
+	"bosschat/internal/pkg/enums"
 )
 
 type ToolSpec struct {

internal/pkg/toolx/mcp_tool.go

@@ -4,8 +4,8 @@ import (
 	"encoding/json"
 	"strings"
 
-	"cs-agent/internal/pkg/dto/request"
-	"cs-agent/internal/pkg/errorsx"
+	"bosschat/internal/pkg/dto/request"
+	"bosschat/internal/pkg/errorsx"
 )
 
 func BuildMCPToolCode(serverCode, toolName string) string {